Topic 3. STRUCTURE OF DOG ARTICLES AND MAIN DEVIATIONS FROM

Accustoming a dog to follow the trail of its owner (basic commands “sniff”, “trace”) At the beginning of training a dog to work on a trail, the trainer must choose techniques that could force the dog to sniff the trail, and try to associate them with the command

Rice. 3. Skeleton of a dog
1. skull
2. upper jaw
3. lower jaw
4. teeth
5. cervical vertebrae - 7
6. atlas (first cervical vertebra)
7. epistrophy, axial (second cervical vertebra)
8. thoracic vertebrae - 13
9. last thoracic vertebra
10. lumbar vertebrae - 7
11. sacrum (3 fused vertebrae)
12. caudal vertebrae (usually 18)
13. shoulder blade
14. spine of the scapula
15. neck of the scapula
16. humerus
17. head of the humerus
18. lateral condyle of the humerus
19. elbow joint
20. olecranon (protrusion of the ulna)
21. ulna
22. radius

23. carpal bones
24. hand bones
25. accessory bone
26. metacarpal bones
27. phalanges of fingers
28. sternum
29. handle of the sternum
30. rib
31. costal cartilage
32. pelvis
33. ilium
34. pubic bone
35. ischium
36. femur
37. large skewer
38. kneecap
39. fibula
40. tibia
41. tarsal bones
42. tubercle of the calcaneus
43. metatarsal bones
44. phalanges of toes

http://www.real3danatomy.com/bones/dog-skeleton-3d.html

A dog has the following body systems:

1. Nervous
2. Bone
3. Muscular
4. Blood
5. Respiratory
6. Digestive
7. Urinary
8. Endocrine
9. Reproductive
10. Immune
11. Skin

The health of the animal depends on the harmonious operation of all these systems.

In external description What is important are the systems that make up certain characteristics that characterize a particular breed and its membership in the breed group.

In the dog's body there are:
1) Movement apparatus - systems of bones, ligaments and muscles.
2) Internal organs - systems of digestive, respiratory, urinary and reproductive organs.
3) Integrating the work of all organs of the system: blood and lymph circulation, immune system, endocrine gland system, skin system, sensory organs and nervous system.

Along the body of the animal there is a spine, in which there is a spinal column formed by the vertebral bodies (the supporting part that connects the work of the limbs in the form of a kinematic arc) and the spinal canal, which is formed by the vertebral arches surrounding the spinal cord. Depending on the mechanical load created by body weight and mobility, the vertebrae have different shapes and sizes.

Each vertebra has a body and an arch.

The spine is differentiated into sections that coincide with the direction of action of the gravity forces of tetrapods (Table 1).
Table 1

Sections of the spine and number of vertebrae in a dog

The vertebrae of the cervical spine are movably connected to each other, while the first two have significantly changed their shape: the atlas and epistropheus. The head moves on them. The ribs are attached to the bodies of the thoracic vertebrae. The lumbar vertebrae have powerful articular processes that provide a stronger connection between the vertebral arches, to which the heavy digestive organs are suspended. The sacral vertebrae are fused to form the sacrum. The size of the caudal vertebrae decreases with distance from the sacrum. The degree of reduction of parts depends on the function of the tail. The first 5-8 vertebrae still retain their parts - the body and the arch. In subsequent vertebrae the spinal canal is no longer present. The basis of the tail consists only of the “columns” of the vertebral bodies. In newborn puppies, the tail vertebrae have a low degree of mineralization, so certain breeds of dogs (for example, Airedale Terriers) undergo tail docking (circumcision) at an early age.

The rib cage is formed by the ribs and breast bone. The ribs are movably attached on the right and left to the vertebrae of the thoracic spinal column. They are less mobile in the front of the chest, where the scapula is attached to them. In this regard, the anterior lobes of the lungs are more often affected in lung disease. Dogs have 13 pairs of ribs. They are arched. The breast bone comes in the form of a clearly shaped stick. The chest itself is cone-shaped, with steep sides.

Peripheral skeleton or limb skeleton

The thoracic limb is represented by:

A shoulder blade attached to the body in the area of ​​the first ribs;

The shoulder, consisting of the humerus;

The forearm, represented by the radius and ulna bones;

A hand consisting of the wrist (7 bones), metacarpus (5 bones) and phalanges of the fingers. The dog has 5 fingers, represented by 3 phalanges, the first of the fingers is pendulous and has 2 phalanges. There is a claw ridge at the end of the fingers. The pelvic limb consists of:

The pelvis, each half of which is made up of an innominate bone. The ilium is located above, the pubic and ischial bones below;

The thigh, represented by the femur and the patella, which slides on the femur trochlea;

The lower leg, consisting of the tibia and fibula;

The foot is represented by the tarsus (7 bones), metatarsus (5 bones) and phalanges of the toes (5 toes from 3 phalanges, the first of the toes is pendulous (dewlap) and has 2 phalanges. At the end of the toes there is a claw ridge).

CONNECTIONS

Continuous. This type of connection has great elasticity, strength and very limited mobility. Depending on the structure of the tissue connecting the bones, the following types of connection are distinguished:

With the help of connective tissue - syndesmosis, and if elastic fibers predominate in it - synelastosis. An example of this type of connection is short fibers that firmly connect one bone to another, such as the forearm and tibia bones in dogs;

With the help of cartilage tissue - synchondrosis. This type of connection has low mobility, but provides strength and elasticity of the connection (for example, the connection between the vertebral bodies);

With the help of bone tissue - synostosis, which occurs, for example, between the bones of the wrist and tarsus. As animals age, synostosis spreads throughout the skeleton. It occurs at the site of syndesmosis or synchondrosis.

In pathology, this connection can occur where it normally does not exist, for example, between the bones of the sacroiliac joint due to physical inactivity, especially in old animals;


Rice. 5. Scheme of development and structure of the joint: a – fusion; b – formation of an articular cavity; c – simple joint; d – articular cavity; 1 – cartilaginous bone bookmarks; 2 – accumulation of mesenchyme; 3 – articular cavity; 4 – fibrous layer of the capsule; 5 – synovial layer of the capsule; 6 – articular hyaline cartilage; 7-cartilaginous meniscus

With the help of muscle tissue - synsarcosis, an example of which is the connection of the shoulder blade to the body.

Discontinuous (synovial) type of joint or joints. It provides a greater range of movement and is built more complexly. According to the structure, joints are simple and complex, in the direction of the axes of rotation - multiaxial, biaxial, uniaxial, combined and sliding (Fig. 5).

The joint has an articular capsule consisting of two layers; external (fused with the periosteum) and internal (synovial, which secretes synovium into the joint cavity, thanks to which the bones do not rub against each other). Most joints, except the capsule, are secured by a different number of ligaments. Ligaments often run along the surface of the joint and are attached to opposite ends of the bones, that is, where they do not interfere with the main movement in the joint (for example, the elbow joint).

Most of the bones of the skull are connected using a continuous type of connection, but there are also joints - the temporomandibular, atlanto-occipital. The vertebral bodies, with the exception of the first two, are connected to each other by intervertebral discs (cartilage), that is, synchondrosis, as well as long ligaments. The ribs are connected by intrathoracic fascia, consisting of elastic connective tissue, as well as intercostal muscles and transverse ligaments. The shoulder blade is connected to the body using the muscles of the shoulder girdle, and the pelvic bones are connected to the sacral bone, and to the first caudal vertebrae - by ligaments. The parts of the limbs are attached to each other using different types of joints, for example, the connection of the pelvic bone with the femur occurs using a multi-axial hip joint.

The thoracic limb begins with the scapula, then the humerus, forearm, wrist (7 carpal bones), metacarpus (5 metacarpal bones). The fingers are equipped with strong, non-retractable claws at the end. The thoracic limb is connected to the spine by muscles. The withers are formed above the shoulder blade.

The pelvic (hind) limb begins with the femur, passes into the tibia (tibia and fibula), then into the tarsus (consists of 7 bones). This is followed by the metatarsus (of 4-5 metatarsal bones), then 4 phalangeal toes, ending in claws. Sometimes a rudimentary (dewclaw) finger grows from the inside. It is usually amputated at a young age. The pelvic limb has an articular connection with the pelvis and is fixed by the muscles of the hip group.

Skeleton of the forelimb consists of the shoulder girdle (scapula and rudiment of the clavicle) and the bones of the free limb (humerus, bones of the forearm, wrist, metacarpus and phalanges of the 5 fingers). The size, shape of these bones, and the condition of the joints determine the severity of the withers, angles, set, inclination of the pastern, shape of the paw, height and bonyness of the dog - very important exterior characteristics.
The shoulder blade, with which the forelimb is attached to the chest, is flat, rounded-triangular in shape. The collarbone in dogs is represented by a bone plate up to 1 cm long, lying in a tendon strip in the shoulder-head muscle. The radiograph does not reveal the collarbone. The forearm is formed by two movably connected bones - the ulna (longer) and the radius. The skeleton of the wrist is represented by two rows of bones. The row that is located closer to the forearm consists of 3, and the second row consists of 4 bones of different shapes. The 5 bones of the metacarpus are long, narrow, with a block for articulation with the phalanx. The shortest metacarpal bone is the first, the longest are the third and fourth. The finger bones have 3 phalanges, the third - the claw - carries the claw process.
Skeleton of the hind (pelvic) limb consists of the pelvic girdle and the bones of the free limb.

The pelvic girdle includes 3 pairs of bones - the ilium, pubis and ischium, which, connecting with each other in the acetabulum, form 2 pelvic bones. The latter, merging, give pelvic fusion. The pelvic bones are connected to the sacrum by the iliosacral joint. The continuation of the pelvic girdle in the limb are the femurs, patella, shin bones (tibia and fibula), tarsals (7 bones in 3 rows), metatarsals and phalanges of 4 fingers. The skeleton of the hind limb determines many important exterior characteristics - the top line, the shape of the croup, the stance, the length of the lower leg, the angles of the joints, the shape of the paw, which in turn determines such an important indicator as the nature of the dog’s movements.
The deficiencies and defects of the limbs that dog breeders encounter and which they usually seek to correct belong to three groups - defects in the shape and size of the bones, defects in the joints and defects in the musculo-ligamentous apparatus of limb movements. The causes of defects can be genetic or acquired (injuries, diseases, improper cultivation). Although in Lately More and more often you come across examples! successful correction of limb defects by surgery (elimination of the consequences of injuries), however, given the role of fine anatomical details and coordination of limb movements in the overall impression of the animal’s exterior, surgical techniques cannot be considered adequate for the correction of non-traumatic limb defects.
To correct defects associated with irregular shapes and sizes of bones, it is first necessary to comply with optimal conditions for the general formation of the skeleton. D-hypovitaminosis (rickets) is one of the main causes of curvature, thinning and other deviations in the size and shape of the bones of the extremities.

STRUCTURE OF THE DOG'S SKULL

Dog skull 1.
Occipital bone. 2. Parietal bone. 3. Frontal bone. 4. Lacrimal bones. 5. Nasal bone. 6. Upper jaw. 7. Incisive bone. 8. Temporal bone. 9. Zygomatic bone. 10. Lower jaw.

Dental system

Dental system of a puppy and an adult dog

The structure of the dental system is an extremely important element of a dog’s exterior.

Teeth (dentes) are very strong organs that serve to capture and hold food, for biting it, gnawing and grinding it, as well as for defense and attack. Based on their function, structure and position, teeth are divided into incisors, canines and molars. The teeth are located on the lower and upper jaws, forming dental arcades or arches.

The International Canine Federation FCI has issued instructions on a unified designation system and teeth index values ​​in order to avoid discrepancies in identifying and assessing teeth at international exhibitions. Teeth are designated by initial letters from the Latin name; the sequence in the numbering of indices in all groups of teeth is the same, i.e. from the middle of the jaw in both directions and from front to back.

Teeth are divided into incisors, canines, and molars.

Incisors (dentes incisivi) - located behind the lips, three on each side, designated by the letter I.

Among the incisors there are:

Hooks – the most front teeth, the right and left hooks are next to each other,

Middle incisors - located immediately behind the toes,

The edges are the outermost of the incisors.

Fangs (dentes canini) - placed behind the incisors, one on each side on the upper and lower jaws, designated by the letter C.

Molars are divided into premolars (or premolars) and molars (molars).

Premolars (dentes premolares) - located behind the fangs in the amount of 4 on each side on each jaw, designated by the letter P.

The last group of permanent molars (dentes molares) follows the premolars, 2 pieces on the upper jaw and 3 pieces on the lower jaw; denoted by the letter M.

A complete set of teeth for an adult dog has the following formula:

Incisors I = 3/3;

Fangs C = 1/1;

Premolars P = 4/4;

Molars M = 2/3.

Therefore, a complete set of permanent teeth in an adult dog consists of 42 teeth.

Just like a person, a dog's teeth change once in a lifetime. The first teeth are called baby teeth (dentes decidui). They begin to erupt at the beginning of the puppy's fourth week of life. Around the end of the fourth month, baby teeth begin to fall out. In the sixth or seventh month, tooth replacement ends. By the age of 1.5 years, the teeth are already fully formed.

A set of primary teeth consists of 32 teeth (some authors consider 28 teeth). Each half of the puppy's jaw has 3 incisors, 1 canine and 4 premolars, for a total of 32 teeth. Milk teeth differ in appearance from permanent teeth; they are smaller and thinner, looking like needles. Primary teeth are characterized by a very tight fit to each other, but with age, as the jaw grows and enlarges, the gaps between the teeth increase.

Puppies are born without teeth. The incisors appear first, around the fourth week of life. And in the third month they begin to wear down and stagger. Initially, the internal incisors (hooks) fall out, then the middle incisors follow, and in the fifth month the lateral incisors (edges) are replaced. Primary canines are usually replaced by permanent canines at 6 months. Primary premolars grow in between 4-8 weeks, with the exception of P1, which usually grows in when the dog is 5-6 months old. P1 - the first molar grows only once and is immediately permanent. Molars, the back molars, grow only once and therefore never change. They should grow by the end of the 7th month. Baby teeth begin to fall out as permanent teeth grow, which gradually grow and at the same time put pressure on the roots of baby teeth. Due to this pressure, teeth become loose and fall out.

The structure of the tooth includes the crown, neck, root,

The crown is the part of the tooth that protrudes from the dental alveoli above the gum surface. The shape of the crown is different for different teeth: for incisors it is wedge-shaped, for canines it is cone-shaped, and for molars it is tuberculate.

The roots of a tooth, numbering from one to three, are located in the dental socket of the jaw, in which they are strengthened by connective tissue - periodontium. Single-rooted teeth include incisor canines and first (1st, 2nd) premolars. The root of the tooth is covered with bone tissue - cement.

The neck of a tooth is a narrow transition from the root to the crown. The gum is attached to the neck. The basis of the tooth is dentin, a special calcified connective tissue. In the crown area, dentin is covered with very durable, highly calcified epithelial tissue - enamel.

The correct functioning of the dental system is possible only if the teeth are located relative to each other in a certain order. The mutual arrangement of the teeth of the upper and lower jaws is called the bite. Only a correct bite allows the most productive use of physical efforts for mechanical processing of food in the oral cavity.

There are four main types of bite:

Scissor,

Pincer-shaped or straight,

Snack,

Underbite.

Most traditional dog breeds have a scissor bite, typical of the wild type. With this bite, the incisors of the lower jaw adjoin the inner surface of the incisors of the upper jaw, and the canines of the lower jaw fit into the spaces between the edges and canines of the upper jaw, and the sliding surfaces of the canines of the upper and lower jaws have a minimum gap between them.

Pincer bite (straight) is characterized by the closure of the incisors of the upper and lower jaws end to end, like in pincers.

Underbite occurs when the lower jaw is relatively shortened. With this bite, a gap appears between the sliding surfaces of the incisors. Underbite is often complicated by the occurrence of inclination of the incisors and partially canines. In this case, the inclined position of the roots of the incisors and canines can be observed on the radiograph.

An underbite (“bulldog” bite) is really typical for bulldogs, boxers, bullmastiffs, and pugs. With this bite, not only the lower incisors, but also the canines protrude beyond the line of the upper incisors. The overbite can be tight, in which the gap between the upper and lower incisors is minimal, or with a departure, in which there is a more or less significant distance between the incisors.

Numerous studies by breeders show that the shape of the bite is largely hereditary. Anomalies in the dental system may indicate a dog’s possible homozygosity not only for the genes for this trait, but also for many other alleles, which may almost certainly include genes that cause general weakening of the body and loss of constitutional strength.

Much attention is paid to the problems of full teeth in dogs. For some breeds, having a full set of teeth is absolute. For others, the requirements are somewhat relaxed. Congenital dental anomalies include: an increase (polyodontia) or a decrease (oligodontia) in their number, anomalies in location, shape and structure. Such phenomena as oligodontia and polyodontia can be diagnosed both at the time of litter activation and after the change of teeth.

Poly- and oligodontia have been discovered in all types of domestic animals, and the genetic cause of these anomalies has already been proven.

The following main mechanisms of their occurrence are distinguished:

1) splitting of the tooth germ;

2) fusion of tooth germs;

3) development of an additional tooth germ in the dental plate;

4) the absence of one or more rudiments in the dental plate.

Incisive oligodontia can manifest itself in different ways:

The teeth are of normal size, but their number is less - four or five instead of the required six;

The two teeth grow together from the roots to the top of the crowns, forming one larger, normally shaped tooth. If this happens on one side, then five teeth grow, and if on two, then four;

The two outer teeth are fused by their roots, the crowns of the teeth are separated by their apices. A so-called double tooth is formed.

Polyodontia occurs in a typical or atavistic form, which is characterized by the presence of supernumerary teeth inside the dentition and which is almost physiological and atypical, when supernumerary teeth grow outside the dental sockets, sometimes even outside the oral cavity. Pseudopolyodontia is most often associated with retention of primary teeth. Supernumerary teeth may appear as a double tooth. Polyodontia is often a consequence of thyroid deficiency. Some breeds have an increased incidence of polyodontia on the incisors. For example, the standard dachshund periodically produces individuals with seven upper incisors. Similar cases have also been reported in German Shepherds and Collies. It is important that the size of the teeth corresponds to the size of the jaw, which largely guarantees their correct location in the dentition - without the development of misalignment. Sometimes in dwarf and toy breed dogs the teeth are too large in relation to the jaw and cannot be arranged in an even line, which leads to the so-called misalignment. Disorder may also be associated with underdevelopment of the lower jaw. As experience shows, the degree of hereditary conditioning of disorder is quite high. In some cases, there is a so-called misalignment, which manifests itself in the inclination of the dentition in a certain direction.

Deviations in teething are often observed, when permanent teeth erupt while milk teeth have not fallen out, and a double tooth is formed, most often a canine, or even a double row of teeth. Such anomalies are characteristic of disturbances in the activity of the pituitary gland - thyroid - parathyroid gland system, which also occurs when the genome is unbalanced.

A thorough examination of the dental system sometimes reveals an abnormal approach of the roots of the teeth - root convergence. With this anomaly, the pressure produced by the roots of the teeth does not dissipate on the jaw tissue, but on the contrary, strong local pressure arises, which over time leads to trophic disorders in the gums and surrounding tissues. Divergence of the roots, or otherwise divergence of the crowns, occurs during the period of replacement of baby teeth as a result of a delay in their loss and leads to the development of rare teeth.

Another type of dental anomaly is tooth retention, in which the tooth is not in the dentition, but in the thickness of the jaw bone.

The shape of the bite and any deviations from the complete dental formula in most cases are determined by the polygenic system, which can be considered as an indicator of an unsuccessful combination of gene blocks in the genotype, which can lead to multiple undesirable consequences. It is advisable to exclude carriers of these anomalies from breeding.

Muscular system

Muscular system
Plays an important role in the exterior and models the dog’s body in relief. Mobility and flexibility of the body, active muscle activity (dog muscles have few tendons) are the distinctive features of the animal. In order to save muscle energy, the dog prefers not to stand, but rather to lie down. The muscles of the limbs, back and lower back are of particular importance for the movement of the dog. No less important are the muscles of the chest and abdomen, which ensure breathing, and the muscles of the head, primarily the chewing muscles, which allow powerful clenching of the jaws.

Smooth (vascular walls);

Striated (skeletal muscles);

Cardiac striated (in the heart).

Skeletal muscles are represented by a large number (more than 200) muscles. Each muscle has a supporting part - connective tissue stroma, and a working part - muscle parenchyma. The more static load a muscle performs, the more developed its stroma is. In the muscle stroma, continuous tendons are formed at the ends of the muscle belly, the shape of which depends on the shape of the muscles. If the tendon is cord-shaped, it is simply called a tendon. If it is flat, then it is an aponeurosis. In certain areas, the muscle includes vessels that supply it with blood and nerves that innervate it. Muscles can be light or dark, depending on their function, structure and blood supply. Each muscle, muscle group and all musculature of the body are covered with special dense fibrous membranes - fascia. In order to prevent friction of muscles, tendons or ligaments, soften their contact with other organs, and facilitate sliding during large ranges of movement, gaps are formed between the sheets of fascia, lined with a membrane that secretes mucus, or synovium, into the resulting cavity. These formations are called mucous or synovial bursae. Such bursae are located, for example, in the areas of the elbow and knee joint, and their damage threatens the joint.

Muscles can be classified according to several criteria. By form:

Lamellar (muscles of the head and body);

Long, thick (on limbs);

Sphincters (located at the edges of the openings, having neither beginning nor end, for example, the sphincter of the anus);

Combined (composed of individual bundles, for example muscles of the spinal column).

According to the internal structure:

Dynamic (muscles that perform dynamic loads; the higher a muscle is located on the body, the more dynamic it is);

Statodynamic (static function of the muscle during support, holding the joints of the animal in an extended form when standing, when under the influence of body weight the joints of the limbs tend to bend; muscles of this type are stronger than dynamic muscles);

Static (muscles bearing a static load; the lower the muscles are located on the body, the more static they are).

By action:

Flexors (flexors);

Extensors (extensors);

Adductors (adduction function);

Abductors (abduction function);

Rotators (rotation function).

The work of muscles is closely connected with the organ of balance and, to a large extent, with other sense organs. Thanks to this connection, the muscles provide balance to the body, precision of movements, and strength.

Thus, as a result of the joint action of muscles with the skeleton, certain work is performed (for example, an animal moves). During operation, heat builds up.

Therefore, in the warm season, with intense work, dogs may experience overheating of the body - heatstroke.

In cold weather, animals need to move more to avoid hypothermia.

physiology of skeletal muscles

There are muscles various shapes and magnitude. Some are small, others are large, some are weak, others are more powerful. Look at a diagram of a dog's muscles and note the variety of their shapes.

The muscles work together to provide the animal with grace and power. They function in three in various ways: isometric, concentric and eccentric contractions.

Isometric contractions occur when a muscle contracts without making any movement. For example, when standing, isometric contractions provide stability.

Concentric contractions occur when a muscle shortens and produces movements in the joints. Observed mainly with constant movements, such as protraction (moving forward) or retraction (moving backwards), of the limbs and with any movement of the neck or back.

Eccentric contractions occur when a muscle gradually relaxes after a contraction. They provide constant movements, eliminating the resulting jerky unstable movements; also play a shock-absorbing role in the landing phase after a jump.

Skeletal muscles have high elasticity and powerful contractility. Its contractions occur under the influence of nerve impulses coming from motor neurons, so the contraction mechanism is considered a generated process. The process of muscle relaxation is not a generated process. Compared to the initial impulse for their contraction, this is rather a natural relaxation of the muscles as a result of the cessation of nerve impulses from motor neurons.

The muscle has two types of sensory nerve endings: the sensory apparatus (Golgi) and the muscle spindle.

Through the Golgi apparatus of nerve endings, impulses, based on the feedback principle, enter the brain and report on the state of the muscle; this process is called proprioception. The Golgi apparatus is most often located at the junction of muscle and tendon.

The muscle spindle of nerve endings prevents excessive stretching of muscle fibers. The muscle spindle, as its name suggests, wraps around the muscle belly. Having stretched to its length, the muscle spindle sends nerve impulses that initiate a rapid reflex response of motor neurons, in turn inducing immediate contraction of muscle fibers. This prevents overstretching and possible tearing of muscle fibers. This is a protective reflex.

When muscle contracture (persistent muscle contraction) develops, the muscle fibers remain contracted. This may cause spasm. With contracture, normal muscle relaxation does not occur, pain and difficulty in movement occur (limited movement).

When a muscle is overstretched, spasm often occurs. A spasm is a tetanic (intense) contraction of a muscle in response to overextension or injury, causing the muscle to lose its ability to release stiffness. However, a microspasm, or point of tension, is a small area of ​​spasm that affects only a few fibers of the muscle bundle. Microspasm over a period of time has a cumulative effect and causes a more severe spasm.

Sometimes the muscle tension lasts beyond the maximum permissible time, and the muscle fibers are torn. This immediately causes muscle spasm and initiates an inflammatory response with swelling of the injured area. During the healing process, new connective tissue is formed, which grows randomly within the ordered muscle fibers. Unfortunately, these scars reduce the ultimate strength of the muscle and also impair its elasticity and firmness. Massage helps reduce the amount of scar tissue that forms by kneading and rubbing the tissue after preheating it. Additionally, stretching is an excellent massage technique for preventing or eliminating scar tissue formation.

Minor inflammation often occurs in the muscle fibers of muscles subjected to intense physical activity. This is a normal process that promotes the formation of new muscle fibers. It is often seen in the early stages of training or in growing dogs. It is very important that any inflammatory reaction does not go unnoticed, otherwise scar tissue may develop. Cold hydrotherapy and deep massage can be used to relieve inflammation. These techniques stimulate blood circulation, due to which the tissues are saturated with new portions of oxygen and nutrients, which speeds up healing. In addition, scar tissue is destroyed inside the muscle fibers.

Fig.7. Dog musculature, superficial layer.
1. nasolabial lift
2. muscles of the auricle
3. zygomatic muscle
4. cervical saphenous muscle
5. sternohyoid muscle
6. sternomastoid muscle
7. prespinatus muscle
8. levator scapulae muscle
9. tendon strip (rudiment of the clavicle)
10. brachiocephalic muscle
11. cervical and thoracic part of the trapezius muscle
12. infraspinatus muscle
13. latissimus dorsi muscle
14. deltoid muscle
15. triceps brachii muscle (long and short heads)
16. deep pectoralis minor muscle
17. rectus abdominis muscle
18. external oblique muscle
19. aponeurosis
20. internal oblique muscle
21. sartorius muscle
22. tensor fascia lata
23. gluteus medius muscle
24. superficial gluteus maximus muscle
25. semitendinosus muscle
26. biceps femoris muscle
27. levator caudalis muscle
28. tail abductor muscle

Fig.8. Dog musculature, deep layer.

1. temporal muscle
2. masseter muscle
3. nasal muscle
4. buccal muscle
5. parotid salivary gland
6. maxillary gland
7. depressor auricle muscle
8. occipital muscle
9. adductor muscle of the auricle
10. digastric muscle
11. orbicularis oculi muscle, secular part
12. orbicularis oris muscle
13. sternomastoid muscle
14. brachiocephalic muscle
15. plaster muscle
16. serratus cervicalis muscle

17. prespinatus muscle

18. infraspinatus muscle
19. rhomboid muscle
20. teres major muscle
21. serratus pectoralis muscle
22. triceps brachii muscle (long and short heads)
23. deltoid muscle
24. scalene muscle (part)
25. rectus abdominis muscle
26. intercostal muscles
27. transverse abdominis muscle
28. serratus posterior muscle
29. longissimus dorsi muscle
30. iliocostalis muscle
31. sartorius muscle
32. gluteus medius muscle
33. superficial gluteus maximus muscle
34. semimembranosus muscle
35. semitendinosus muscle
36. quadriceps femoris muscle

Fig.9. Musculature of a dog, front view (frontal).
1. sternohyoid muscle
2. sternomastoid muscle
3. tendon strip
4. mastoid muscle
5. brachiocephalic muscle
6. prespinatus muscle
7. deltoid muscle
8. superficial pectoralis major muscle
9. extensor carpi radialis
10. long abductor pollicis
11. biceps brachii

Musculature of the dog. View from the back (caudal side) 1) protruding. point of the croup. 2) base of the tail. 3) maklok 4) muscle levator of the tail 5) muscle of the depressor of the tail 6) gluteal. middle muscle7) superficial. big berries. muscle8) internal obturator muscle 9) biceps 10) semitendinosus femoris 11) semimembranosus 12) gracilis 13) gastrocnemius muscle.

CENTRAL NERVOUS SYSTEM

Brain

The following sections are distinguished in the brain (Fig. 7):

Big brain;

Telencephalon (olfactory brain and cloak);

Diencephalon (visual thalamus (thalamus), epithalamus (epithalamus), hypothalamus (hypothalamus), peritothalamus (metathalamus);

Midbrain (cerebral peduncles and quadrigeminal);

Diamond brain;

Hindbrain (cerebellum and pons);

Medulla.

The brain is covered with three membranes: hard, arachnoid and soft. Between the hard and arachnoid membranes there is a subdural space filled with cerebrospinal fluid (its outflow is possible into the venous system and into the lymph circulation organs), and between the arachnoid and soft - the subarachnoid space.


Rice. 7. Brain: 1 – cerebral hemispheres; 2 – cerebellum; 3 – medulla oblongata; 4 – olfactory bulbs; 5 – optic nerve; 6 – pituitary gland

The brain is the highest department of the nervous system, controlling the activity of the entire body, uniting and coordinating the functions of all internal organs and systems. Here there is a synthesis and analysis of information coming from the senses, internal organs, and muscles. Almost all parts of the brain take part in the regulation of autonomic functions (metabolism, blood circulation, respiration, digestion). For example, in the medulla oblongata there are centers of respiration and blood circulation, and the main department that regulates metabolism is the hypothalamus, and the cerebellum coordinates voluntary movements and ensures the balance of the body in space. In pathology (trauma, tumor, inflammation), the functions of the entire brain are disrupted.

Spinal cord

The spinal cord is covered with three membranes: hard, arachnoid and soft, between which there are gaps filled with cerebrospinal fluid. In dogs, the length of the spinal cord averages 78 cm and weighs 33 g.

Peripheral nervous system

In the peripheral nervous system, it is customary to distinguish three parts - somatic (connecting centers with skeletal muscles), sympathetic (associated with the smooth muscles of the blood vessels of the body and internal organs), parasympathetic (associated with smooth muscles and glands of internal organs) and trophic (innervating connective tissue).

Autonomic (autonomic) nervous system

Sympathetic (innervation of smooth muscles of blood vessels, internal organs, glands), the centers of which are located in the chest lumbar region spinal cord;

Parasympathetic (innervation of the pupil, salivary and lacrimal glands, respiratory organs, organs located in the pelvic cavity), whose centers are located in the brain.

The peculiarity of these two parts is their antagonistic nature in supplying internal organs, that is, where the sympathetic nervous system acts stimulatingly, and the parasympathetic nervous system depressingly. For example, the heart is innervated by the sympathetic and vagus nerves. The vagus nerve, which extends from the parasympathetic center, slows down the heart rate, reduces the magnitude of contraction, reduces the excitability of the heart muscle and reduces the speed of the wave of irritation through the heart muscle. The sympathetic nerve acts in the opposite direction.

The central nervous system and the cerebral cortex regulate all higher nervous activity through reflexes. There are genetically fixed reactions of the central nervous system to external and internal stimuli - food, sexual, defensive, orientation, the appearance of saliva at the sight of food. These reactions are called innate or unconditioned reflexes. They are provided by the brain, spinal cord stem, and autonomic nervous system. Conditioned reflexes are acquired individual adaptive reactions of animals that arise on the basis of the formation of a temporary connection between a stimulus and an unconditioned reflex act. An example of such reflexes is the fulfillment of natural needs while walking. The center for the formation of this type of reflex is also the cerebral cortex.

Skin covering

LEATHER

In the skin covered with hair, the following layers are distinguished (Fig. 6).

1. Epidermis (epidermis) – outer layer. This layer determines the color of the skin, and keratinized cells are exfoliated, thereby removing dirt, microorganisms, etc. from the surface of the skin. Hair grows here: 3 or more guard hairs (thick and long) and 6-12 short and delicate undercoat hairs.

2. Dermis (actual skin):

The pilar layer, which contains the sebaceous and sweat glands, hair roots in hair follicles, muscles that lift the hair, many blood and lymphatic vessels and nerve endings;

A mesh layer consisting of a plexus of collagen and a small amount of elastic fibers.

The dermis contains scent glands that produce a characteristic odor for each breed. In hairless areas (nose, paw pads, scrotum in males and nipples in females), the skin forms patterns that are strictly individual for each pet.

3. Subcutaneous base (subcutaneous layer), represented by loose connective and adipose tissue.

This layer is attached to the superficial fascia that covers the dog's body.

It stores reserve nutrients in the form of fat.

Rice. 6. Diagram of the structure of skin with hair: 1 – epidermis; 2 – dermis; 3 – subcutaneous layer; 4 – sebaceous glands; 5 – sweat gland; 6 – hair shaft; 7 – hair root; 8 – hair follicle; 9 – hair papilla; 10 – hair follicle

SKIN DERIVATIVES

Sebaceous glands. Their ducts open into the mouths of the hair follicles. The sebaceous glands secrete a sebaceous secretion, which, by lubricating the skin and hair, gives it softness and elasticity.

Sweat glands. Their excretory ducts open to the surface of the epidermis, through which a liquid secretion is released - sweat. Sweat glands dogs have a little. They are located mainly in the area of ​​the crumbs on the paws and on the tongue. The dog does not sweat with its entire body; only rapid breathing through an open mouth and the evaporation of fluid from the oral cavity regulate its body temperature.

Mammary gland. They are multiple and located in two rows on the lower part of the chest and abdominal wall, 4-6 pairs of hills in each row. Each colliculus contains several gland lobes that open into nipple canals at the tip of the nipple. There are 6-20 nipple canals in each nipple.

Hair. These are spindle-shaped filaments of stratified keratinized and keratinized epithelium. The part of the hair that rises above the surface of the skin is called the shaft, the part located inside the skin is called the root. The root goes into the bulb, and inside the bulb there is a hair papilla.

Based on their structure, there are four main types of hair.

1. The outer coat is the longest, thickest, elastic and hard, almost straight or only slightly wavy. It grows in large quantities on the neck and along the spine, on the hips and in smaller quantities on the sides. Wire-haired dogs usually have a large percentage of this hair type. In short-haired dogs, the outer hair is absent or located in a narrow strip along the back.

2. Guard hair (covering hair) – thinner and more delicate. It is longer than the undercoat and covers it tightly, thereby protecting it from getting wet and abraded. In long-haired dogs, it is curved to varying degrees, which is why they distinguish between straight, curved and curly hair.

3. Undercoat is the shortest and thinnest, very warm hair that fits the dog’s entire body and helps reduce heat transfer from the body during the cold season. It is especially well developed in dogs kept outside during the cold season. Change of undercoat (molting) occurs twice a year.

4. Vibrissa – sensitive hair. This type of hair is located on the skin in the area of ​​the lips, nostrils, chin and eyelids.

There are a large number of coat classifications based on hair quality.

According to the presence of undercoat:

Dogs without undercoat;

Dogs with undercoat.

Based on the identity of their coat, dogs are:

Smooth-haired (bull terrier, Doberman, Dalmatian and others);

Straight-haired (beagle, rottweiler, labrador and others);

Short-haired with feathering (St. Bernard, many spaniels and others);

Wirehaired (terriers, schnauzers and others);

Medium-haired (collie, spitz, pekingese and others);

Long-haired (Yorkshire terrier, Shih Tzu, Afghan hound and others);

Long-haired with corded hair (poodle, commander and others);

Long-haired shaggy ones (Kerry Blue Terrier, Bichon Frize and others).

Hair color is determined by two pigments: yellow (red and brown) and black. Presence of pigment in pure form gives an absolutely uniform color. If the pigments are mixed, then other colors occur.

Most dogs shed twice a year: in spring and autumn. This phenomenon is called physiological molting. Spring molting is usually longer and more pronounced. Shedding is a dog's natural defense against the summer heat and replaces old hair with new ones. During the summer, dogs mostly have guard hair, and the undercoat falls out. In winter, on the contrary, a thick and warm undercoat grows. When kept at home, dogs have a longer shedding period than those living on the street.

Claws. These are horny curved tips covering the last, third, phalanges of the fingers. Under the influence of muscles, they can be pulled into and out of the groove of the roller. Such movements are well expressed on the fingers of the thoracic limbs of dogs. Claws are involved in the function of defense and attack, and with their help the dog can hold food and dig the ground.

Crumbs. These are the supporting areas of the limbs. In addition to their supporting function, they are organs of touch. The cushion of crumbs is formed by the subcutaneous layer of skin. A dog has 6 crumbs on each thoracic limb, and 5 on each pelvic limb.

Dental system

An adult dog has 42 teeth, 20 of which are located on the upper jaw and 22 on the lower jaw. Depending on their location on the jaw, structure and purpose, a dog’s teeth are divided into four groups: incisors (Jncisivi), fangs (Canini), false-rooted (Praemolares) and indigenous (Molares).

Each jaw, on the left and right sides of the imaginary midline, dividing the jaws in half, has three teeth, which are called incisors - front, middle and extreme. Behind them are the canines, and behind each canine there are four premolars. The first premolar is usually very small. Subsequent teeth gradually increase in size towards the molars such that the fourth premolar in the upper jaw is the largest tooth and is called the “carnassial” tooth. In size and purpose in the lower jaw it corresponds to the first molar. The lower jaw has three molars on each side, and the upper jaw has two.

A puppy is born without teeth. Baby teeth begin to erupt at 4 weeks of life. At the 2nd month of life, 28 baby teeth grow, 14 in the upper and 14 in the lower jaw.

Baby teeth are devoid of roots, so they do not last long for a young dog. As soon as her permanent teeth begin to develop, which grow in the bony part of the upper and lower jaw, the baby teeth fall out. They are replaced by permanent teeth.

A permanent tooth consists of three sections: root, neck and crown. The root grows into the bone tissue of the jaw and is not visible. The neck of the tooth protrudes from the soft tissues of the jaw, which ends in a dental crown, consisting of hard and very durable enamel.

The arrangement of individual teeth in the jaw and the position of the teeth of the upper jaw relative to the teeth of the lower jaw play a big role when eating food. Naturally, over time, individual disturbances and changes may occur in the dog’s dental apparatus, which can equally affect the teeth of the upper and lower jaws.

The age of the dog is also determined by the teeth, which has diagnostic value (Fig. 13).

You can determine the age of a dog by its teeth (Table 3).

In dogs, breed-specific changes in the bite of the incisor teeth (the position of the dental arcades and their closure) are noted. In animals with an average head length, the upper and low incisors oppose each other (pinscher, some Great Danes), in long-headed animals (shepherd dogs, greyhounds), the upper incisors protrude slightly forward in relation to the lower ones, and in short-headed animals (pugs, boxers), the lower incisors and canines protrude in front of the upper incisors and canines


Rice. 12. Arcades of dog teeth: J – incisors; C – fangs; P – premolars; M – molars


Rice. 13. Age-related changes dog teeth: a – 6 months; b – 1.5-2 years; c – 3 years; g – 5 years; d – 9–10 years
table 2

Dog dental formula
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Table 3

Determining the age of dogs by teeth


Gums are folds of mucous membrane that cover the jaws and strengthen the position of the teeth in the bone cells. The hard palate is the roof of the oral cavity and separates it from the nasal cavity, and the soft palate is a continuation of the mucous membrane of the hard palate; it is located freely on the border of the oral cavity and pharynx, separating them. The gums, tongue and palate may be unevenly pigmented.

Several paired salivary glands open directly into the oral cavity, the names of which correspond to their location: parotid, mandibular, sublingual and zygomatic. The secretion of the glands is alkaline, it is rich in bicarbonates, but does not contain enzymes. Its main role is to lubricate bolus food. Lack of saliva leads to difficulty swallowing: food can get stuck in the throat or esophagus. Tonsils are organs lymphatic system and perform a protective function in the body. The entrance to the pharynx is called the pharynx.

The swallowing process begins in the mouth with the formation of a bolus of food, which rises to the hard palate with the tongue and moves towards the pharynx.

Digestive and respiratory organs

PHARYNX

A bolus of food in the pharynx is detected by sensory receptors located in this section. The nasopharynx is closed reflexively by raising the soft palate, while the Eustachian tubes and larynx are closed by the epiglottis. The pharyngeal muscles contract, the esophageal sphincter relaxes, and the bolus of food enters the esophagus.

ESOPHAGUS

After contraction of the pharyngeal muscles, the annular pharyngeal sphincter relaxes and the bolus of food enters the esophagus. This leads to the initial peristaltic movement of the bolus down the esophagus into the stomach. The second peristaltic wave is often observed when the esophagus is completely empty.

A dog's esophagus can return food from the stomach to the mouth (vomiting). The opening of this organ into the stomach opens relatively easily.

STOMACH

The gastric mucosal barrier is designed to protect the stomach from ingested irritants, hydrochloric acid and pepsin. This barrier consists of a layer of mucus covering the epithelium, the epithelial cells themselves, and submucosal tissue rich in blood vessels. In addition to the physical protective barrier, mucus contains phospholipids with hydrophobic properties, which complement the action of pepsin inhibitors and act as a hydrochloric acid buffer. Violation of the protective barrier leads to inflammation (gastritis) and subsequent ulceration of the gastric mucosa (ulcer). The digestion process becomes painful.

The animal may begin to vomit after eating, or the pet may refuse to eat due to lack of appetite, which will subsequently lead to weight loss.

When food enters the stomach, the fundus relaxes to reduce intragastric pressure. This process is called receptive relaxation. In its absence or inflammatory processes, the pressure in the stomach quickly increases, which leads to vomiting associated with food intake.

The sight, smell and taste of food, together with its presence in the stomach, stimulates the secretion of hydrochloric acid and pepsinogen. In the presence of hydrochloric acid, pepsinogen is converted into active pepsin, which is quickly inactivated when the pH decreases. This occurs naturally as stomach contents pass into the duodenum, where pancreatic bicarbonates neutralize stomach acid. Hydrochloric acid and pepsin begin the process of digesting food by hydrolyzing proteins and starch, and lipase - fats. High body temperature inhibits the release of enzymes. Therefore, in summer, dogs eat mainly during the cooler parts of the day. The highest enzyme activity is for bread, milk and meat.

The stomach has a pacemaker that produces five slow waves every minute. Three types of stomach movements have been identified:

Digestive - it occurs after swallowing food. These are slow, successive contractions of the fundus of the stomach that push food toward the pylorus, where the food is crushed and fluid is released through the pylorus;

Intermediate - it occurs after digestion of food in the stomach, after a transition period of reduced gastric contractions;

Non-digestive is the emptying peristaltic contractions of the entire empty stomach, intended to move the remaining contents into the duodenum.

Solid food, ground into chyme, is sent to the duodenum in a certain order: first liquids, then proteins and carbohydrates, then fats. Indigestible material remains in the stomach. Foods rich in calories reduce the rate of gastric emptying, and, conversely, low-calorie foods are digested and removed from the stomach faster. Food enters the dog’s stomach after eating food in half an hour to an hour and remains there for 6-8 hours.

INTESTINES

There are small and large intestines.

Small intestine

The intestinal mucosa is more specialized for the digestion and absorption of food. The epithelial cells lining the inner surface of the small intestine are called enterocytes. The mucous membrane is collected in folds called villi. Each villi is well supplied with blood vessels and has a dead-end lymphatic vessel. These vessels transport absorbed nutrients from the small intestine to the liver and other parts of the body. The duodenum has a relatively porous structure and is capable of secreting a large volume of fluid into the lumen. The degree of permeability decreases accordingly in the jejunum, ileum and large intestine, where only fluid resorption takes place. This preserves fluid in the body and prevents diarrhea.

The bulk of proteins is digested in the small intestine to amino acids under the action of pancreatic enzymes. They are absorbed into enterocytes through specific transporters, and then transported to the liver through the portal vein. Carbohydrates (dogs get most of their carbohydrates in the form of starches) are broken down in the small intestine into glucose and other monosaccharides by pancreatic enzymes. In enterocytes, glucose is rapidly released into the bloodstream and transported to the liver through the portal vein. Dietary fats mainly consist of triglycerides, which can be easily broken down by bile salts into glycerol and fatty acids and absorbed, while cholesterol and phospholipid can be digested by dogs, but not as efficiently. This occurs under the influence of bile secreted by the liver and stored in the gallbladder. Since the cell membrane of enterocytes consists of lipids, the absorption process occurs passively and is often accompanied by the absorption of vitamins dissolved in fats. Inside the enterocytes, fatty acids are converted to triglyceride and attached to lipoproteins to form chylomicrons, which are excreted into the milk duct for transport to the main circulatory system and subsequently to the liver and other tissues.

Thus, any disruption of the small intestine (for example, rotavirus infection) can cause diarrhea and anorexia (loss or lack of appetite) due to the virus damaging the enterocytes of the villous apex). Highly digestible foods are necessary to reduce enzyme costs and increase the area of ​​absorption, thereby achieving a good level of nutrient intake. Eating small amounts of food does not overload the digestive and absorption capabilities of the intestines and reduces the risk of diarrhea.

Colon

In the large intestine, the final hydrolysis of nutrients occurs with the assistance of enzymes of the intestinal tract and enzymes of microorganisms. The most active activity of the intestinal microflora is observed in the colon: absorption of water and electrolytes, which is necessary for the formation of feces and the prevention of dehydration; fermentation of food residues by abundant bacterial flora (from nitrogen-rich food residues, bacteria produce large amounts of ammonia, which is absorbed and enters the liver through the portal vein, where it is processed into urea, which is excreted by the kidneys). Due to strong peristaltic contractions, the remaining contents of the large intestine enter the rectum through the descending colon, where feces accumulate. The release of feces into the environment occurs through the anal canal (anus). The anus has two sphincters: deep, made of smooth muscle fibers, and external, made of striated muscles. In dogs, there are two depressions on its sides - the right and left sinuses, into which the paranal glands open, secreting a thick secretion that emits a specific odor.

Thus, once in the oral cavity, the food is ground and chopped, rather than chewed with the teeth. Then it is moistened with saliva and enters the stomach through the pharynx and esophagus, where the process of its decomposition into simpler substances begins. Absorption of nutrients occurs in the intestines, and undigested food remains, mainly fiber, are excreted through the rectum.

Respiratory system

While passing through the airways, the inhaled air is moistened, warmed, cleared of dust, and also examined for odors using the olfactory organ. With exhaled air, some water (in the form of steam), excess heat, and some gases are removed from the body. Sounds are produced in the air passages (larynx).

The respiratory organs are represented by the nose and nasal cavity, larynx, trachea and lungs.

NOSE AND NASAL CAVITY

The paranasal passages communicate with the nasal cavity paranasal sinuses. The paranasal sinuses are air-filled, mucous-lined cavities between the outer and inner plates of some of the flat bones of the skull (for example, the frontal bone). Because of this message inflammatory processes from the mucous membrane of the nasal cavity can easily spread to the sinuses, which complicates the course of the disease.

LARYNX

TRACHEA

The length of the trachea depends on the length of the neck, and therefore the number of cartilages in dogs ranges from 42 to 46.

LUNGS

Connective tissue unites them into a paired compact organ - the right and left lungs. The right lung is slightly larger than the left, since the heart, located between the lungs, is shifted to the left (Fig. 14). The relative weight of the lungs is 1.7% relative to body weight.

The lungs are located in the chest cavity, adjacent to its walls. As a result, they have the shape of a truncated cone, somewhat compressed from the sides. Each lung is divided into lobes by deep interlobar fissures: the left - into three, and the right - into four.

The frequency of respiratory movements in dogs depends on the load on the body, age, health status, temperature and humidity of the environment.

Normally, the number of inhalations and exhalations (breathing) in a healthy dog ​​varies within significant limits: from 14 to 25-30 per minute. This range width depends on a number of factors. Thus, puppies breathe more often than adult dogs because their metabolism is more active. Bitches breathe more frequently than males. Pregnant or nursing dogs breathe more frequently than non-pregnant dogs. The breathing rate can also be affected by the breed of the dog, its emotional state, and the size of the dog also affects it. Small breed dogs breathe more often than large ones: miniature pinscher, the Japanese Chin breathes 20-25 times per minute, and the Airedale - 10-14 times. This is due to different rates of the metabolic process, and, as a result, greater heat loss.

Breathing largely depends on the dog’s body position. Animals breathe easier when they stand. In case of diseases accompanied by damage to the heart and respiratory organs, animals take a sitting position, which helps to facilitate breathing.


Rice. 14. Topography of a dog’s lungs, right view: 1 – trachea; 2,3,4 – cranial middle lobe of the lung; 5 – heart; 6 – diaphragm; 7 – dorsal edge of the lung; 8 – basal edge of the lung; 9 – stomach; 10 – ventral edge of the lung

The breathing process is also affected by the time of day and season. At night, when at rest, the dog breathes less frequently. In summer, when the weather is hot, as well as in stuffy rooms with high humidity, breathing becomes more frequent. In winter, dogs' breathing at rest is even and imperceptible.

Muscle work sharply increases the dog's breathing. The factor of the animal's excitability is also of certain importance. The appearance of a stranger or a new environment can cause rapid breathing.

Patella. Patella.

Patella. Patella.

The function of the patella is to prevent friction between the tendon and the trochlear groove of the femur. If there were no patella, then the tendon would rub directly against the bone, causing it to degenerate and eventually fracture. "Dislocation" means "falling out" or "slipping out."
Medial luxation of the patella. Luxation patella, or kneecap disorder, is a common hereditary problem in small dog breeds such as toy poodles and Yorkshire terriers. Research has conclusively shown that patella luxation is a hereditary trait, and dogs with this genetic problem should not be used in a breeding program.
A dislocated patella is the most visually noticeable sign of a deviation in the development of the entire limb.
The type and extent of the deformity varies and includes: decreased forward rotation and varius of the proximal femur, medial displacement of the quadriceps muscles, hypoplasia of the medial and hyperplasia of the lateral femoral condyle with flattening of the trochlea, internal rotation and valgus of the tibia, displacement of the tibial crest in medial direction and turn the fingers inward.

Patella dislocation has several degrees.
Clinical division of patella dislocations.
I DEGREE.
The movement is normal, but sometimes cases of habitual dislocation of the kneecap are possible, in which the dog holds the limb suspended due to pain. Straightening the limb leads to reduction of the dislocation.
II DEGREE.
Genu varum, toes turned inward, frequent dislocations during movement with inability to step on the paw. If the violation is observed on both sides, then the dog steps on its paws, but avoids straightening them. There is rotational instability of the knee joint up to 30 degrees and inward rotation of the tibial crest when the limb is straightened.
III DEGREE.
Genu varum with inward rotation of the distal part of the limb. With a unilateral dislocation, the dog does not step on the paw; with bilateral movement, it is carried out in short steps on half-bent legs. The quadriceps muscle cannot straighten the joint. There is obvious rotational instability of 30-60 degrees. Internal rotation of the tibia crest and tibia. Medial dislocation of the patella is difficult to reduce and immediately recurs. Sometimes accompanied by a sprain or rupture of the anterior cruciate ligament with a “drawer” sign.
IV DEGREE.
The dog moves in the same way as with a third degree dislocation; very young dogs move in leaps and bounds. Genu varum with bent knees is observed. Rotation of the tibial crest 60-90 degrees. Surgery is required.
If a dog has been carrying its paw suspended for a long time, in most cases there is a rupture of the quadriceps muscle, and there is very little chance of restoring normal function of the limb without arthrodesis.
Very young dogs may not show obvious signs and symptoms of patellar luxation, but with age there is a definite tendency for the limb to deteriorate and mild degrees of patella gradually progress to more severe degrees. This mechanical process of impact on the kneecap is irreversible. Therefore, at the slightest sign of a hint of this disease, you should consult a doctor. This disease can affect the dog's organs and cause skeletal deformation. Dislocation problems are usually found on the inside of the patella. Very often, bitches begin to suffer from this disease after giving birth, since bearing puppies and increasing body weight have an undeniable effect on the dog’s limbs.

The operation is recommended in cases where grade D or E dysplasia is detected, with subluxation or complete dislocation of the femoral head, as well as in the presence of signs of secondary osteoarthritis.The operation can and even preferably be performed at the age of 4-5 months, since it is in puppyhood that it is better tolerated and rehabilitation occurs faster. In addition, with degrees of dysplasia D and E with subluxation at the age of 4-5 months. at the age of 10-12 months. More severe forms of osteoarthritis will already be observed, which will greatly complicate recovery after surgery. The disadvantages of this operation include a relatively long recovery period. This is due to the fact that after the operation, the pelvic limb is stabilized only by a thickened capsule and muscles stabilizing the joint, and this may take time. But an important advantage of this method is the ability to “forget” about the existence of dysplasia (of course, after rehabilitation of the limb) for the entire life of the dog, moreover, in physical activity There are practically no restrictions for life as well. It is also important that during this operation no artificial components remain in the body.

Patella luxation or displacement of the patella from its normal position in the femur trochlea (see figure) is a relatively common cause of lameness in small and medium breed dogs.The severity of the disease varies from mild, in which the dog only occasionally limps, to severe, in which movement causes discomfort or pain to the dog and the dog is practically unable to step on the affected limb (walks on three legs). Most dogs with early stages of the disease have a relatively normal gait and only occasionally limp or even not limp at all. If the disease affects both hind legs, then the inability to move normally becomes obvious.
Veterinarians use a special classification to assess the condition and degree of displacement and deformation of the bones of the hind limbs. We need to remember that most patella dislocations are considered congenital, although some may be associated with trauma or contusion. The luxation may not be obvious at first, but if the dog is born with abnormalities in the femur and tibia, it is only a matter of time before the kneecap becomes dislocated from its normal position.
It is believed that patella luxation is an inherited disease, so mating of dogs with this disease should be limited. Clinically, the disease can manifest itself soon after birth, but most often it is detected after 4 months. The predisposition to it is higher in females. At the same time, the mechanism of inheritance has not been fully studied, but is presumably polygenic, i.e. associated with more than one gene, such as dysplasia. It is recommended that all puppies be checked by a veterinarian for this disease.

lateral patella displacement

On the left - the normal structure of the hind limb, on the right - bone deformation and associated medial patella displacement

Triple pelvic osteotomy
information provided by the Zoovet clinic
The operation consists of surgically giving the acetabular component of the hip joint a more correct angle, which consists of intersecting the three pelvic bones (iliac, pubic and ischial), followed by fixing the sawn segment (iliac) with a Z-shaped plate. The operation is actually extra-articular, i.e. The hip joint itself is not affected. Performed on dogs aged 5 months and older. But the recommended optimal age is 9-10 months. since at this age the intensity of growth of the bone apparatus sharply decreases, but at the same time the processes of formation and regeneration of the skeletal system are still high. Puppies tolerate this operation better and recover faster. The operation is ineffective when severe forms dysplasia, especially with secondary osteoarthritis, which significantly reduces its applicability. In general, the presence of osteoarthritis in hip dysplasia reduces the effectiveness of this surgical procedure. The disadvantage of triple pelvic osteotomy is also the narrowing of the pelvic cavity, which can lead to dysfunction of the pelvic cavity organs (rectum, bladder). In addition, after this operation, the amplitude of abduction of the pelvic limb to the side decreases.
Total hip replacement
The operation consists of a complete replacement of both the acetabular and femoral components of the hip joint with a prosthesis (titanium alloy, polymer). The operation is indicated for severe forms of pathology; if performed correctly and with good compatibility of the implant, it gives good results and this is, of course, an important advantage. But even with a high-quality operation, the body’s reaction to the prosthesis is partly unpredictable. There are aspects of the success of an operation that cannot be predicted.
S FORUM.

Dysplasia (Greek dys - deviation from the norm, plasis - formation, formation; dysplasia - developmental disorder). Hip dysplasia is an anatomical defect of underdevelopment of the acetabulum, which poses a risk of impaired musculoskeletal functions of the hind limbs. This disease has a multiple nature, in the development of which an important role is played by: fast growth during childhood and adolescence of the animal, as well as “excessive” feeding. In addition to true dysplasia, these factors can lead to secondary disruption of the formation upper section hips and, as a consequence, to hip dysplasia. In addition, changes in the anatomical structure of the lumbar vertebrae lead to secondary hip dysplasia. It should be noted that changes in the spine lead not to anatomical, but to “functional” hip dysplasia with consequences characteristic of true hip dysplasia.
Hip dysplasia is a common congenital disease of dogs, mainly large breeds such as St. Bernards, Newfoundlands, Labradors, Shepherds, Bobtails, Golden Retrievers, Chow Chows, Rottweilers, etc.
Most researchers consider this disease to be hereditary. However, no specific gene responsible for dysplasia has been identified. Therefore, there was an opinion that it was inherited on the basis of many genes. In this case, the presence of dysplasia genes in an animal may not manifest itself as a disease. Thus, hereditary predisposition leads to the disease in the presence of “favorable” environmental conditions that interfere with the normal development of the hip joints of young animals.
“Favorable” conditions are considered: the anatomical structure of the pelvis (acetabulum of the pelvis and head of the femur), which is very vulnerable during the period of development up to six months of age; various injuries to the hind limbs during the development of the animal; loads associated with excess weight of the animal during its development; overfeeding animals at an early age.
The diagnosis of hip dysplasia based on clinical and radiographic examination can be made as early as 4-6 months of age. However, this diagnosis can finally be made in an adult dog at the age of 8-12 months, and for especially large breeds - at 18 months.
Signs of dysplasia may include:
- the dog gets tired quickly during a walk;
- every 10 - 15 minutes sits down or lies down to rest;
- has difficulty getting up after sleep;
- hind limbs tremble;
- wobbles strongly when walking;
- hock joints are abnormally close together.
Dysplasia develops during the first 6 months of life as a result of disproportionate development of the bone structures and soft tissues of the hip joints.
At birth, the femoral head and acetabulum in puppies are formed primarily from cartilage. Bone formation and changes in the position of the femoral head depend on the process of endochondral ossification. When a dysplastic joint forms, a redistribution of the load occurs: more than half of the body weight during walking falls on the anterior-superior edge of the cavity. As a result, microcracks and cartilage deformations are formed. Clinically this is manifested by lameness and pain.
Long-term consumption of a diet high in calcium also leads to impaired bone formation. Excessive consumption of phosphorus may slow down the normal absorption of calcium from the intestine due to the formation of non-absorbable compounds - phytates. Excess vitamin D in the diet causes a delay in the normal formation of bones and joints. Also, the development of dysplasia can
increase excess vitamins C and B1 in the diet.
The only measure to combat dysplasia is widespread veterinary control and culling of identified sick animals from breeding.
It is recommended not to overload the dog’s body, to provide the pet with proper nutrition(if a dog’s diet is overloaded with calories and proteins, then under the influence of excess weight, bones, joints, and ligaments become distorted), walk more often, but for less time.

Hip dysplasia
1.
1. General information and statistics Hip dysplasia (HJD) is a congenital disease based on heredity. And it spreads very quickly due to the use of some generally accepted methods of selection, for example, inbreeding, line breeding, etc.
The main seriousness of this disease lies in the inheritance of the so-called. a loose hip joint, which then leads, in addition to various stresses acting during the development of the animal, to underdevelopment of the acetabulum of the pelvic bone, which also contains the underdeveloped and modified head of the femur.
The hip joint is a movable joint of bones formed by the articular cavity of the pelvis (acetabulum) and the head of the femur. The hip joint is simple, triaxial, spherical in shape.
The main movements in the joint - flexion and extension, as well as rotation - are limited and determined by the structure of the ligamentous apparatus, the structure of the articular relief and muscles. The joint capsule is extensive, reinforced by powerful ligaments that limit the range of movements in the joint.
Hip dysplasia is a congenital pathology when there is subluxation of the hip joint, against which a dislocation occurs. This malformation involves all elements of the hip joint - the acetabulum, the head of the femur with surrounding muscles, ligaments, and capsule.
Hip dysplasia was first described in 1935. Among German shepherds in the United States, according to Sheils, up to 75% of dogs suffered from this defect (1959), and according to Henrikson, 7% (1969). According to Schunkard (1969) from 1962 to 1968. Of the 1,725 ​​German Shepherds in the US Armed Forces, 22.5% were culled for this defect. Rejection rates close to fifty have been found in studies of German Shepherds in almost all countries (Wamberg, 1967). According to Schlaaf, in 1971 in the GDR this percentage was 35.8. A study conducted in the largest concentration of dogs in Poland (Warsaw) revealed 21% of animals affected by dysplasia. According to statistics from Scandinavian countries, about 90% of dogs show obvious symptoms of THD.
In a number of breeds, DTBS has reached significant prevalence. German shepherds, St. Bernards, Newfoundlands are especially often affected by it, and among small dogs - Pekingese, Affenpinschers and pugs. This anomaly is also observed in Rottweilers (Editor's note: Please note that the Rottweiler is one of the original breeds when breeding the black terrier), boxers, Great Danes, and bulldogs, while greyhounds are free from this defect. There is no dependence of the disease on gender and age.
Dysplasia in 89% of cases affects both hip joints, in 3.3% - only the joint of the right hip, in 7.7% - only the joint of the left.

2. Etiology

As an etiological factor leading to deviation from the normal development of the hip joint and surrounding muscles, some authors consider a malformation of the anlage, while others consider a delay in the development of the hip joint during intrauterine life of the fetus. They try to explain developmental deviations by changes in vitamin balance, hormonal disorders and other reasons.
There is an assumption that the development of PTHD occurs due to insufficient interaction between the acetabulum and the femoral head during intrauterine life of the fetus: the earlier the femoral head and acetabulum are deprived of close contact with each other, the more pronounced the anatomical and clinical-radiological symptoms of dysplasia appear.
The occurrence of hip joint laxity was also observed as a result of a kind of hormonal play (estrogenic), which seems to most plausibly indicate the pathogenesis of the disease.
Medical researchers have identified the majority of mothers who gave birth to children with PTHD, the presence of cardiovascular diseases or toxicosis of pregnancy, accompanied by disturbances in protein and salt metabolism in the mother and the fetus. The same thing happens with our dogs.
Numerous studies have convincingly proven that THD is genetic, i.e. hereditary disease. According to Mitin, its trigger point is the hereditarily transmitted “factor of underdevelopment” of the joint.
Statistics from all authors show that the percentage of puppies with severe lesions from parents with severe degrees of the disease is higher.
Table 1. Dependence of the state of the hip joint in the descendants of the first generation on the state of the hip joint of the parents
Joints of parents % of affected offspring
according to Tarkevich (all breeds) according to Robinson (all breeds)
Both parents are healthy 17.5 28.4
Male is healthy, female is sick 41.4 48.2
Male is sick, female is healthy 38 41
Both parents are sick 45 84 Scientists differ on the issue of the dependence of the disease on the sex of the animal. Thus, according to Vanderlip (all breeds), males get sick 1.2 times more often. Tarkevich points to an equal percentage of patients of both sexes (all breeds). According to Mitin (all breeds, 1982), the incidence is higher in females. But in this case, reference is made not to the linkage of the trait with gender, but to hormonal influence. According to DROS (1991-1993), the incidence rate in German shepherds among males is 25.4% and among females - 28.5%. Thus, the figures given by various authors, are quite close, and in all cases the percentage of patients in females turns out to be higher.
When the parents were free from dysplasia (selection in two generations), the percentage of healthy puppies reached 76. If one of the partners was free from dysplasia, the percentage of healthy puppies ranged from 47 to 50. Björn-fors considers the type of inheritance of DTHD as autosomal dominant with the probability of phenotypic manifestation of the gene in the population is 60%.
Hereditary predisposition plays a decisive role in the occurrence of DTHD. However, this disease can also occur in dogs obtained from completely healthy parents. The degree of inheritance of THD, according to Swedish authors, is 55-60%. Statistical assessment of the origin of the disease within the entire dog population is variable and depends on many factors.
It has been established that environmental factors significantly influence the final result of the formation of joints and the clinical manifestations of THA.
Another predisposing factor is considered to be overload of the hip joints in growing young animals. The critical period for the development and stabilization of the hip joints is considered to be the age of the puppy from birth to 60 days of life. During this period, soft and elastic bones and cartilage, nerves and immature muscles are especially susceptible to stress and weight loads. With the correct load, the development of the joint components occurs synchronously. By 6 months of life, joint ossification and muscle mass are already sufficient to prevent the development of THD under normal conditions.
From this point of view, the puppy with the best marketable appearance at the release of the litter immediately falls into the risk group for THD. This is worth thinking about for those clubs where the main criterion for an excellent assessment of the litter is the “elephant” weight of the puppies, even if they can barely move.
Undoubtedly, an overweight puppy significantly increases the load on the hip joints. In this case, the nature of nutrition also plays an important role: protein foods help build muscle mass, balanced mineral nutrition, vitamins and microelements affect the rate of growth and development of body tissues, the development and ossification of the skeleton. A lack or excess of minerals, trace elements and vitamins can lead to irreversible changes in the hip joints. Thus, according to some data, a lack of ascorbic acid in a growing body under stress leads to the development of THD. Carbohydrate foods (porridge) promote the formation of adipose tissue, thereby aggravating the condition of the joints. Rickets has a negative effect on bone tissue in general and can become the starting point for the development of PTHD. Delayed ossification of joint elements caused by various reasons also predisposes to THA.
The question still remains open whether the dysplastic state of the joint is the cause of weakness of the pelvic muscles, or, conversely, muscle weakness is primary for the development of the process in the joint.
A number of researchers point to the connection between the hip joint and the anatomical structure - straight hip position.
Swedish scientists pointed to the role of female sex hormones during the period of growth and development of the body in the occurrence of THD. In the experiment, it was possible to induce THD in offspring by feeding female sex hormones to whelping bitches and their puppies in the first months of life.
An important factor contributing to the development of THA is the excess movement in the joint noted by most researchers, which increases even with normal weight and muscle mass load on joints during the period of growth and development of long bones. In an experiment on puppies with an initial mild degree of the disease, some of them, raised in enclosures with limited opportunity movement, significantly stabilized my joints. The control group, in which movements were not limited, subsequently had severe forms of the disease.
In this regard, one cannot help but dwell on the now fashionable system of “show” training among dog breeders, when a two- to three-month-old puppy begins to be “pulled”, troted excessively, and almost harnessed for towing. Not to mention the fact that such “training” weakens the puppy’s psyche; the load on the hip joint seems criminal. Up to 8-10 months, the main training for a puppy should be free movements, games with peers and swimming, and everything in moderation, with a gradual increase in loads. It should be taken into account that some “groovy” puppies do not know how to stop when walking, so the owner himself must dose the load. It seems very harmful to weak joints when a puppy chases a rapidly galloping adult dog. Early (up to 10-12 months) work on apparatus, regardless of their width, height and degree of complexity, seems extremely irrational. The resulting joint overload and even minor injuries are at least a stress factor and can contribute to the development of the disease.

3. Development pathological process

The disease begins with disturbances in the osteochondral apparatus of the hip joints, in particular, with underdevelopment of the upper edge of the socket (acetabulum), which leads to its gradual flattening. The alignment of the socket and the femoral head is disrupted. The forces in the joint are redistributed, the loads on the upper and anterior surfaces of the acetabulum increase. Looseness occurs in the joint under the influence of the weight of the body and the movements of the animal. Overloaded areas of the femoral head are subject to increased wear and tear, which is not compensated for by regenerative processes. Bone growths (exostoses) form on the edges of the acetabulum and on the femoral neck. They grow in cartilage degenerative changes. The wearing head of the femur becomes deformed, changing from spherical to conical or mushroom-shaped.
Changes occur in the ligamentous apparatus of the joint and surrounding tissues. To hold the joint, its capsule is compacted. The deposition of calcium salts begins in it. Flabby muscles are unable to support the joint. Wear and tear of joint tissue and degenerative processes in it cause inflammatory phenomena - arthritis, which occurs acutely or chronically, with periodic exacerbations, pain and lameness.
The range of motion in the joint becomes more and more limited, the animal spares the affected limb. Gradually, all elements of the joint are involved in the process. The blood supply to the femoral head is disrupted. The ligaments become loose, the joint capsule is stretched, and the nerve endings are injured, increasing the pain. Subluxations and complete dislocations develop, and the configuration of the joint is disrupted. The displacement of the femoral head always occurs upward and outward. The calcified capsule loses its elasticity. Over time, there may be complete degeneration of the joint structures (arthrosis), rupture of the joint capsule, stiffness or immobility (ankylosis) of the joint, as well as systemic damage and osteodystrophy.
All of the above phenomena lead to disability of the dog, sometimes raising the question of killing.
The pathogenesis of congenital hip dislocation is caused by pre-dislocation and dysplasia of the joint, characterized by hypoplasia of the acetabulum, small size of the femoral head and slower ossification, anterior rotation of the upper end of the femur, and anomalies in the development of the neuromuscular system in the hip joint area. Changes are observed in the shape and structure of the flattened cavity, femoral head, articular cartilage, articular capsule, ligaments and muscles. The acetabulum is not only flattened, but also elongated in length: its upper edge is underdeveloped, as a result of which the roof is sloping and there is no bone support for the femoral head on top.
The flattening of the acetabulum often increases due to the thickening of the cartilaginous layer of the bottom of the acetabulum and the development of connective tissue at the bottom. With the formation of a dislocation, these changes increase: the upper arch may disappear, the cavity takes on a triangular shape and becomes even flatter. The femoral neck, which develops in the absence of a bone support, is shortened, the upper end of the femur, together with the head, rotates even more anteriorly. The femoral head is significantly smaller than normal, it is deformed, and the ossification nucleus appears in it later. The joint capsule takes on an hourglass shape and is subjected to sharp morphological changes: it stretches, following the head moving upward and backward.

4. Clinical manifestations of the disease

Fortunately for owners, only 20% of dogs with diseased joints have obvious clinical manifestations (according to Tarkevich). The slightest deviations do not lead to noticeable clinical manifestations in the dog and, as a rule, remain invisible to its owner. A full picture of the disease is usually observed in dogs older than 5-6 months.
The time for distinct clinical signs to appear depends on the individual characteristics of the animal. However, this usually happens no later than the first year of life, which is probably associated with the beginning of training and training.
In other cases, the symptoms are absent or so mild that they do not affect the well-being and working use of the dog.
In mild cases, the puppy or young dog will have slight weakness of the hind legs, with occasional slight lameness in one or both legs with prolonged movement or heavy exertion. Movements may remain free, but the dog becomes less resilient and is reluctant to perform vault jumps over the barrier, and the gait becomes loose.
Starting from the second stage, subluxation or dislocation may occur, even reaching a complete lateral displacement of the femoral head due to the extremely crushed acetabulum of the femur.
In severe cases, pain and rapid fatigue are observed after moving or standing for a long time, the dog has difficulty getting up, and limps when moving, and the lameness is stronger at the beginning of the movement. The weakness of the limbs and their instability on a smooth floor are noticeable. Movements are difficult, the gait is usually stiff and tense. When landing, the hip turns inward (rotation), and the dog takes an unnatural position. Subsequently, atrophy of the gluteal muscles develops, asymmetry of the pelvis may be observed, the greater trochanter of the femur is clearly defined, and when the dog moves, the work of the joint is unnaturally noticeable. Compensatory hypertrophy of the muscles of the forelimb girdle is possible. With subluxation or dislocation, the paw turns outward. By sparing the limb, the dog can stop leaning on it completely. Passive abduction of the hip to the side is usually limited, and shortening of the affected limb may be observed. In severe forms of the disease, the clicking symptom during passive rotation of the hip may be positive. When the hip is abducted to the side, it is possible to feel the displacement of the femoral head relative to the acetabulum. Particularly noticeable is bilateral dysplasia, in which dogs are unable to lift and use their affected limbs. They either crawl or move forward in a sitting position, resting their front paws and spreading their hind paws different sides. During diagnosis, both joints should be examined simultaneously.
Sometimes, in severe cases, clear movement disorders appear immediately after birth, in the first weeks or months of life. Congenital hip dislocation is diagnosed in a newborn puppy by its inability to push off normally with its hind limbs and move around; by his forced position on his stomach with his hips spread to the side. Puppies that by the 10th day of life have not regained the ability to move on a par with normal littermates must be destroyed. During the final examination of the litter, each puppy should be examined in motion. One should be wary of “late-running puppies”, puppies with hind limbs spreading on a non-slip surface and not holding a stance. In this case, puppies with minor deviations can be left until re-examination after 2 weeks, but even with complete normalization of movements, they are the first at risk. At the same time, it has been noticed that puppies who, at the age of 30 days or more (and some as adults), take the “chicken-tobacco” position when resting with their limbs straightened and extended back, feel quite comfortable in it and easily jump out of it, subsequently have radiographically healthy joints. However, this position still needs final confirmation with statistical material.
In older (2-6 months) puppies, you should be alert to weakness of the hindquarters after short runs (the puppy tends to sit or lie down, often throwing his butt over), poor coordination and avoidance of movements associated with a large load on the joint (jumping up in place, sudden changes directions at full gallop, etc.).
Later, clinical dysplasia is characterized by alternating lameness of one or the other hind limb, the dog lies more willingly, rises with difficulty, reluctantly and with tension walks up the stairs, showing symptoms of pain in the limbs. In the late stage, the disease reaches atrophy of the gluteal muscles (as a result of inactivity and disruption of the correct motor function of the back of the body), and the process of ossification and hardening begins in the joints.
Dogs aged 4-5 years have already hardened adhesions in the hip joints.

5. Diagnostics

Not every clinically healthy dog ​​is free from dysplasia. There was no connection between the degree of LTD on the X-ray and the severity of clinical manifestations, as well as the degree of decrease in the functions of the affected limb, although dogs with incorrect posture and visible deviations in the structure of the hind limbs show the largest% of patients on X-rays.
There are reports in the literature that congenital anomalies of the hip joint can be identified in puppies by palpation, noting a freer displacement of the femoral head in the socket. It seems that an ordinary dog ​​handler or veterinarian is not up to the task.
The final conclusion is made only after bone growth is complete, i.e. at approximately one year of age according to the results of an x-ray examination.
The X-ray diagnostic method after the formation of the osseous-ligamentous apparatus is completed is the only reliable and reliable one.
A uniform system for X-ray testing for THD for FCI member countries was developed by the Utrecht Congress, dedicated to the fight against THD. A single form, classification of severity and terminology has been established.
The minimum age for X-ray testing is 12 months, and for large breeds, including the black terrier, at least 18 months. The photographs are identified by the animal’s personal mark, which must be placed on the photograph, indicating the registration number, breed, and date. Marking "right-left" is required. Two photographs are required, taken strictly with the dog in the supine position using sedatives, relaxants or anesthesia.

To obtain high-quality images, you must follow some rules:
On the day of the examination, the dog should not be fed; it should be given a good walk before the examination.
Bitches should not be monitored during or immediately after estrus.
Even calm dogs require the use of anesthesia or sedatives, as well as muscle relaxants. Relaxation of skeletal muscles helps to obtain a more accurate picture of the joints.
The dog is fixed strictly on its back. For the main (first) projection of the image, the limbs should be fully straightened in all joints, pulled back as far as possible and rotated inward by about 15 degrees.
It is unacceptable to examine whelping and lactating bitches, although x-ray examination is absolutely harmless to the body.
It seems possible to limit yourself to taking one shot in the main projection.

6. Basic radiological characteristics of the hip joint1. The Norberg angle (cranio-acetabular) is measured between a straight line connecting the geometric centers of the femoral heads and a line drawn from the center of the head along the anterior-outer edge of the glenoid cavity. Marking of the radiograph is carried out, according to the method, with a special tablet-protractor, followed by measuring the angle with a conventional protractor.
2. Index of penetration of the femoral head into the glenoid cavity - is the ratio of the femoral head, covered with the upper edge of the acetabulum, to the radius of the head. We code this parameter as “coverage”.
3. The tangential angle is located between the horizontal drawn through the anterior-outer edge of the articular cavity and the tangent, which is a continuation of the cranial contour of the joint space. Normally, the tangent passes below the horizontal, forming a negative angle, or coincides with it, forming an angle equal to zero. The tangent directed above the horizontal forms a positive angle characteristic of the pathological process. In practice, we denote this parameter as “tangent”.
4. The neck-diaphyseal angle is formed by the intersection of the axes of the neck and diaphysis (body) of the femur.

A normal hip joint has the following characteristics:
joint angle (Norberg angle) 105 degrees or more, often up to 115-125 degrees;
tangential angle is negative or equal to zero;
the anterior edge of the glenoid cavity to its outermost end has a uniform concavity and is pointed;
The joint space is narrow, uniform, and concentrically located in the cavity.
the femoral head is inserted into the socket by 1/2 - 2/3, i.e. head penetration index is equal to or greater than 1
the femoral neck has no deposits, the neck-diaphyseal angle is 145 degrees.
Depending on the intensity of changes in the joint (or joints), four degrees of dysplasia are distinguished.

Dysplasia 1st degree:
Norberg angle 100-105 degrees;
flattening in the area of ​​the anterior edge of the cavity;
delicate layers on the neck of the femur;
still normal fixation of the femoral head;
the articular surfaces are congruent, but the gap is somewhat widened.

Dysplasia 2 degrees:
Norberg angle is less than 100 degrees;
distinct stratifications on the neck of the femur;
weak fixation of the femoral head or its slight deformation;
somewhat flattened glenoid cavity.

Dysplasia 3 degrees:
Norberg angle 90 degrees;
strongly flattened acetabulum;
phenomena of osteoarthritis;
articular surfaces are not congruent;
deformation of the femoral head and its subluxation.

Dysplasia 4 degrees:
The following should be considered signs of THD on an x-ray:
The Norberg angle is less than 105 degrees.
The head penetration index is less than one.
Wide and uneven joint space.
Positive tangential angle with rounded anterior outer edge of the acetabulum.
When deciphering an x-ray, it should be taken into account that minor differences between the gradations of normality and pathology, noticeable in the image, are purely quantitative, without a qualitative transition.

7. Results of X-ray diagnostics of thoracic hip joint
Each country, if there is a centralized check, has its own system for entering the results of an X-ray examination into the dog’s breeding documents. A veterinarian entitled to such a check puts a stamp in the pedigree indicating the date of the check and the dog's brand number.
* In Germany, the verification stamp is placed in the lower right corner of the pedigree, and on the back at the top is the stamp of the Zukhtburo: “a”. In the I - II generation of ancestors in healthy (free from dysplasia) dogs, “a” zuerkannt is indicated indicating the condition of the joint: Normal (normal), Fast normal (almost normal) and noch zugelassen (still acceptable).
A specialist from the Central Breeding Bureau enters the verified dog into the register and puts the corresponding stamp in the pedigree for dogs free from dysplasia. In some countries, this function is assigned to the veterinarian who checked the dog or to the veterinary council.
In 1974 in Utrecht, the Netherlands, under the auspices of the scientific commission F.C.I. A working conference was held on the problem of hip joint dysplasia.
During the conference, a commission was formed whose task was to recheck the terminology for the classification of hip dysplasia and develop a form for a single valid international certificate. W. Brass (Hannovег), U. Frediger (Beгn), L.F. Muller (Derlin), S. Paatsama (Helsinki) and C.C. van der Waterin (Utreht) were elected members of this commission, a representative of the scientific commission F.C.I. N. A. Van der Verden (Niederlande) was elected secretary.
In subsequent years, working meetings of the commission were held many times, which were supported by the work of S.-E. Olsson (Stockholm) and Chg. Saar (Berlin). The commission's report was published in 1978 in the journal "Kleinterpraxis", Band 23, 1978, 3. 169-180,
S. Paatsama, as President of the World Small Animal Veterinary Association with its congress in Barcelona (Spain) in 1980, proposed at the next congress of this organization in 1978 in Las Vegas (U.S.A.) to discuss the issue of international recognition of findings on dysplasia in order to achieve unity with countries , not included in the F.C.I.
I. Bouw (Niederlande), as chairman of the scientific commission of the F.C.I., indicated in his report to the general meeting of the F.C.1. on the need for recognition of an international certificate for hip dysplasia. He announced a working meeting of the countries included in the F.C.I. on hip dysplasia in Hannover (Germany).
Invitations to the congress, which took place on December 12-13, 1981 in Hannover, were sent to all participants through the General Secretariat of the F.C.I. Representatives of the following countries took part: Belgium, Germany, Denmark, Finland, Italy, Yugoslavia, Holland, Norway, Austria, Sweden and Switzerland.
Based on the report of the Commission on Hip Dysplasia published in 1978, radiographs were presented, discussed and described. This has achieved widespread agreement in the description and classification of hip dysplasia.
Scientific Commission F.C.I. proposed, on the basis of the already mentioned report of the commission on dysplasia at a meeting in Hannover, to introduce an international certificate on the status of dysplasia of the hip joints of dogs examined by x-ray and a list of requirements necessary when taking x-rays.
On June 14, 1991, an FCI seminar on dysplasia was held in Dortmund, in which 15 FCI member countries were represented by their specialists.
Since it was not possible to develop a single recognized international classification, the current classifications of various countries must be given on the reverse side of the certificate. The number of countries included in this scheme can be expanded to include countries that adopt this methodology.
The commission suggests following the following recommendations when taking x-rays:
The minimum age of a dog for examination is 1 year; for large breeds, including the black terrier, this minimum age is 1.5 years.
The dogs are identified in a suitable manner (legible tattoo or microchip). These identifying points are indicated in the pedigree and on x-rays.
A necessary condition for identifying x-rays, in addition to the identification code (tattoo number, / microchip /, entry number in the breeding book), is the date of the x-ray examination and marking of the x-ray on the inside of the right or left thigh.
The owner of the dog must confirm in writing that the pedigree of the dog being examined is presented. In addition, he must give permission to store the photograph in the canine association (it is recommended to adopt an article allowing the organization that gives an opinion on the photographs, as well as the union, to use the results of these studies in a certain way).
The veterinarian must confirm that he has verified the dog's identification.
He should indicate what form of anesthesia or sedation was administered and confirm that a sufficient degree of muscle relaxation was achieved.
X-ray images should be archived centrally.
For the expert's opinion, at least one photograph in position I (with the hind legs extended) is required. The second shot in position II (with the hindquarters flexed) can also be used.
The minimum size of the x-ray in position 1 should provide representation of both joints and hips, including the knee joints.
The technical quality of X-ray images should ensure an accurate diagnosis of the picture of dysplasia.
X-rays must be returned if the above requirements are not met.
The conclusion based on the photographs must be made by an authorized person or commission of the union in which the dog is registered.
Each national organization that issues X-ray reports must provide an opportunity to appeal the report. Fundamental questions, which, for example, concern one breed of dog, can be forwarded to the FCI scientific commission.
It should be noted that despite the unification of terminology and classification of DTHD degrees, the marking of pedigrees is not universal, and each country has its own system for checking dogs and marking pedigrees. By decision of the FCI in 1997, a unified system for assessing the hip joints of dogs and marking the pedigree will be introduced in the countries that are members of this organization.
We should be wary of the pedigrees of dogs exported from countries where TBS examination is mandatory, without an inspection stamp, or with a stamp, but without a stamp indicating result “a”. Of course, this applies to dogs taken out as adults, i.e. who have reached the age of verification.
Most foreign countries are implementing programs to combat THD with varying degrees of success. The greatest successes have been achieved in countries where X-ray diagnostics of breeding dogs and their offspring is universal, mandatory and carried out centrally, with the gradual exclusion of sick and disadvantaged animals from breeding. Programs based on voluntary inspection and culling, as well as measures carried out only by individual breeders, cannot significantly influence the dynamics of disease incidence.
Orthodox programs that propose to use only dogs with completely healthy joints for breeding do not allow the disease to be quickly eradicated due to the nature of its inheritance and the presence of healthy carriers in the population. At the same time, a sharp exclusion from the breeding of a large number of animals that are highly valuable for other economically useful traits will cause irreparable and disproportionate damage to the breed.
When implementing any program, genetic data should be taken into account. A widely spread hereditary disease in the breed, in the first years of the fight against it, there is a sharp decline. Subsequently, the process slows down. Geneticists consider mass selection to be the only method of eradicating this polygenically inherited disease from a breed.
Thus, the success of measures to combat THD depends on the organization of breeding work.

V.N. Mitin proposed a table compiled according to the classification approved by the FCI, and assigning letter designations (selection indices) to each gradation.
Table 2. Assignment of selection indices for DTBS (according to Mitin)
TSB condition Selection index X-ray diagnostic signs
Healthy joint a-0 “Ideal” a-1 “No signs of hip joint pain” There are no signs, all parameters are “with reserve”
Stage of predisposition to THA a-2 “Still normal joint” Presence of one of the signs (A, B, C, D)
Stage of predysplasia b “Within acceptable limits” Combination of any two signs
Initial stage of destructive changes with “mild THD” Combination of any three signs
Stage of pronounced destructive changes d "Moderate hip joint injury" Combination of four signs, subluxation in the joint is possible
Stage of severe destructive changes e “Severe THA” Combination of four signs, Norberg angle less than 90, subluxation or dislocation in the joint Each joint, according to the table, is assessed separately. The total result of the condition of the animal's joints is taken according to the worst of its joints, for example if the left joint is “a-1” and the right joint is “c” overall result checks "c". The letter designation becomes an integral part of the nickname and is written before it with a hyphen.
Elbow dysplasia.

Dogs are mammals, therefore, their skeleton is typical of mammals and consists of the same sections.

Mammals have a larger skull than, for example, reptiles.

Mammals are characterized by the presence 7 cervical vertebrae. Both giraffes, which have a very long neck, and whales, which have no neck at all, have the same number of cervical vertebrae. The thoracic vertebrae (usually 12-15 of them) together with the ribs and sternum form the chest.

The lumbar spine is formed by massive, movably articulated vertebrae that provide flexion and extension in this section of the spine. This way the torso can bend and unbend. The number of lumbar vertebrae in different species of mammals can vary from 2 to 9; in a dog there are 6. The sacral spine consists of 3-4 vertebrae, which are connected to the pelvic bones.

The number of vertebrae in the caudal region in dogs can range from 3 to several dozen, which determines the length of the tail.

The girdle of the forelimbs of mammals consists of two shoulder blades, crow bones fused with them, and a pair of underdeveloped clavicles.

The girdle of the hind limbs - the pelvis - in a dog is formed by 3 pairs of pelvic bones. Most mammals, including dogs, have especially developed muscles in the back and limbs.

The dog's mouth, like that of other mammals, contains its tongue and teeth. The tongue is used to determine the taste of food: its surface is covered with numerous papillae, which contain the endings of the taste nerves. The movable tongue moves food around the mouth, which helps wet it with saliva secreted by the salivary glands. Mammalian teeth have roots with which they are strengthened in the sockets of the jaws. Each tooth consists of dentin and is covered on the outside with durable enamel. In mammals, teeth have different structures associated with a specific purpose. In the front of the dog's jaws there are incisors, on both sides of which there are fangs. In the depths of the mouth are the molars.

The muscles of the lower jaw are also very developed, thanks to which the dog is able to firmly hold prey

Skeleton of a dog: 1 – upper jaw; 2 – lower jaw; 3 – skull; 4 – parietal bone; 5 – occipital protuberance; 6 – cervical vertebrae; 7 – thoracic vertebrae; 8 – lumbar vertebrae; 9 – caudal vertebrae; 10 – shoulder blades; 11 – humerus; 12 – bones of the forearm; 13 – carpal bones; 14 – metacarpus; 15 – phalanges of fingers; 16 – ribs; 17 – costal cartilages; 18 – sternum; 19 – pelvic bone; 20 – hip joint; 21 – femur; 22 – knee joint; 23 – tibia; 24 – fibula; 25 – calcaneus; 26 – hock joint; 27 – tarsus; 28 – metatarsus; 29 – fingers

Puppies first develop baby teeth, which later fall out and are replaced by permanent teeth.

All a dog's teeth have a purpose. It uses its molars to tear large pieces of meat.

The outer molars have blunt tips that help chew plant matter. Incisors are designed to separate meat from bones.

The dog's stomach, like that of most mammals, is single-chamber; the intestine consists of the small, large and rectum. In the intestines, food is digested under the influence of the secretions of the digestive glands of the intestine, as well as the juices of the liver and pancreas.

In a dog, like in other mammals, the chest cavity is separated from the abdominal muscular septum - the diaphragm, which protrudes into the chest cavity and is adjacent to the lungs. When the intercostal muscles and diaphragm contract, the volume of the chest increases, the ribs move forward and to the sides, and the diaphragm becomes flat from convex. At this moment, the force of atmospheric pressure forces air into the lungs - inhalation occurs. When the ribs descend, the chest narrows and air is pushed out of the lungs - exhalation occurs.

Internal organs of the dog: 1 – nasal cavity; 2 – oral cavity; 3 – trachea; 4 – esophagus; 5 – lungs; 6 – heart; 7 – liver; 8 – spleen; 9 – kidneys; 10 – small intestine; 11 – large intestine; 12 – anus; 13 – anal glands; 14 – bladder; 15, 16 – genitals; 16 – brain; 17 – cerebellum; 18 – spinal cord

The dog's heart has four chambers and consists of 2 atria and 2 ventricles. The movement of blood is carried out in 2 circles of blood circulation: large and small.

Urine is excreted through the kidneys, a paired organ located in the abdominal cavity on the sides of the lumbar vertebrae. The resulting urine enters the bladder through 2 ureters, and from there it is periodically discharged through the urethra.

Metabolism in mammals, due to the high development of the respiratory and circulatory systems, occurs at high speed. The body temperature of mammals is constant.

The brain of dogs, like other mammals, consists of 2 hemispheres. The cerebral hemispheres have a layer of nerve cells that form the cerebral cortex.

In many mammals, including dogs, the cerebral cortex is so enlarged that it forms folds-gyri, and the more convolutions, the better developed the cerebral cortex and the more nerve cells it contains. The cerebellum is well developed and, like the cerebral hemispheres, has many convolutions. This part of the brain coordinates the complex movements of mammals.

The normal body temperature of a dog is 37–38 °C; puppies under 6 months of age have an average temperature of 0.5 °C higher than that of adult dogs.

Dogs have 5 senses: smell, hearing, vision, touch and taste, but they are not equally developed.

Dogs, like most land mammals, have a good sense of smell, which helps them track prey or detect another dog by scent, even at a considerable distance. The hearing of most dogs is also well developed, this is facilitated by movable ears that capture sound.

The organs of touch in dogs are special long and stiff hairs, the so-called vibrissae, most of which are located near the nose and eyes.

By bringing their heads closer to any object, mammals simultaneously sniff, examine and touch it. The behavior of dogs, along with complex instincts, is largely determined by higher nervous activity based on conditioned reflexes.

Immediately after birth, the puppy’s social circle is limited to its mother and other puppies, among whom it receives its first skills of communicating with the outside world. As puppies grow older, their personal experience with their environment continually increases.

Changes in the environment cause dogs to constantly develop new conditioned reflexes, and those that are not reinforced by stimuli disappear. This ability allows dogs to adapt to changing environmental conditions.

Puppy games (wrestling, chasing, jumping, running) serve as good training and contribute to the development of individual attack and defense techniques.

For any dog ​​owner, knowing at least the basics of your pet's anatomy will be useful. This will help you evaluate its appearance, understand the nuances of behavior and the causes of predisposition to certain diseases, and, if necessary, provide first aid to your pet. From this material you can glean basic information about the dog’s skeletal and muscular system, its internal organs and sensory organs.

Like any vertebrate, the dog has an internal skeleton. Let us remember that this term refers to a set of bones that are connected by bone or cartilage tissue. The bones of the skeleton play both a protective role and are the basis for soft tissues (muscles, for example).

Did you know? Like human fingerprints, each dog's nose has a unique pattern, which is why noseprints are used to identify these pets.

This part of the skeleton is a load-bearing element consisting of vertebral discs, which are connected to each other by cartilaginous formations called intervertebral discs. The connecting discs, on the one hand, provide mobility to the animal’s vertebra, and on the other, act as shock absorbers. The spinal column is conventionally divided into the following sections:

• cervical spine with seven vertebrae, with the two upper vertebrae characterized by increased mobility;
• the thoracic region, consisting of thirteen vertebrae, which serve as the basis for attaching the ribs;
• lumbar region, containing the seven most massive vertebrae;
• the sacrum, also called the sacrum, consists of three fused vertebrae;
• the tail contains up to 23 movable vertebrae, decreasing towards the tip of the tail.

There are three types of skulls in dogs:

Important! The structure of the skull of short-headed dogs (flat muzzle and wide crown) is the cause of respiratory problems in these breeds. Outwardly, this manifests itself as hoarse breathing and increased salivation.

The skull itself is divided into a fixed axial part and a movable part, which includes the lower jaw and hyoid bone. In addition, a dog’s skull is divided into two sections: the brain and the facial. The medulla contains 3 paired bones and 5 unpaired bones, namely:

Dog skull: 1 – incisive bone; 2 – nasal bone; 3 – maxillary bone; 4 – lacrimal bone; 5 – zygomatic bone; 6 – frontal bone; 7 – parietal bone; 8 – temporal bone; 9 – occipital bone; 10 – lower jaw

• frontal bone - paired, both bones form the front part of the skull, partially form the eye sockets, temples, nose;
• parietal bone - paired, both bones are in contact with the frontal bones, forming the parietal part of the skull;
• temporal - paired, both bones partially form the cheekbones, contain the hearing organs, mate with the lower jaw, the masticatory muscles are attached to it;
• interparietal - unpaired, located between the occipital bone and the parietal bones;
• occipital - unpaired, forms the back of the head;
• sphenoid - unpaired, connects to the occipital bone;
• pterygoid - unpaired, takes part in the formation of the nasal cavity;
• ethmoidal - partially forms the brain cavity.

• the nasal bone is paired, the nasal concha is attached to these bones;
• the maxillary bone is paired, these bones partially form the nasal cavity;
• mandibular - steam room;
• incisive - paired, these bones form part of the palate;
• palatine - steam room, partially forms the palate;
• vomer - unpaired, divides the choanae (internal openings of the nasal cavity);
• lacrimal - steam room, forms part of the orbit with the lacrimal opening;
• zygomatic - steam room, partially forms the eye sockets and cheekbones;
• The superior and inferior turbinates are unpaired and form the base of the nasal concha.

In addition to the skull bones, it is important to have an understanding of the characteristics of the dog's teeth. An adult dog has 42 teeth, puppies have 28 teeth. Different breeds may have different bites. There are several types of bite:

• scissor-shaped (aka normal) - the upper and lower incisors are tightly connected, with the lower ones slightly extending beyond the upper ones;
• pincer-shaped - the upper and lower incisors are closed edge to edge;
• undershot - the lower incisors noticeably do not reach the line of the upper ones;
• undershot (or bulldog) - due to the shortened muzzle, the lower jaw protrudes forward in relation to the upper jaw.

Ribs

The dog has thirteen pairs of ribs. These bones are curved in an arc, attached to the vertebrae of the thoracic region and together with the sternum form the rib cage. The anterior ribs are much less mobile than the rest.

The limb skeleton is also called the peripheral skeleton. It includes the thoracic and pelvic limbs. The thoracic limb consists of:

• shoulder blades;
• humerus;
• the radius and ulna bones, which together form the forearm;
• seven small bones that form the wrist, and five bones of the metacarpus along with the fingers that form the hand;

The pelvic limb includes:

• five pelvic bones;
• the femur and patella, which make up the thigh;
• the tibia and fibula, which form the lower leg;
• seven tarsal bones and five metatarsals, together with the toes, making up the foot;
• phalanges of the fingers (the first finger has 2 phalanges, the other four have three).

Muscular system and skin

Muscles provide the dog with movement - flexion, extension, rotation. There are three types of muscle tissue:

• smooth, making up the walls of blood vessels;
• striated, attached to the skeletal base, more than two hundred such muscles;
• cardiac.

Dog muscles: 1 - frontal; 2 - chewing; 3 - sternothyroid; 4 - brachiocephalic; 5 - trapezoidal; 6 - deltoid; 7 - shoulder; 8 - triceps; 9 - wide back; 10 - chest; 11 - abdominal external; 12 - gluteal; 13 - tensor fascia of the thigh; 14 - semitendinosus; 15 - biceps femur

The skin consists of several layers:

• the outer epidermis, from which hair grows and dead skin sloughs off;
• the main one, called the dermis, in which nerves, blood vessels, glands, etc. are hidden;
• subcutaneous, consisting of fat and connective tissue.

Internal organs

Inside the dogs are various organs, interconnected into several systems. Below is basic information about the internal organ systems.

With the help of the digestive system, the dog’s body receives many substances necessary for its functioning in the form of food, and also removes undigested residues and metabolic products.

The food swallowed by the dog passes through the esophagus into the stomach. where, under the influence of gastric juice and enzymes produced by the pancreas, it turns into a homogeneous mass. This mass moves along small intestine. In the process of movement, the body secretes the necessary substances from this mass, which, with the help of enzymes and bile produced by the liver, enter the body through the intestinal walls.

Food undigested by the body enters the large intestine, where under the influence of a new portion of enzymes and thanks to the activity of microorganisms, feces. Feces are eliminated from the body through the anus.

With the help of the respiratory system, the dog inhales air, saturating the body with oxygen, and exhales a mixture of carbon dioxide, water vapor, etc. Through the nose, larynx, and trachea, air is directed to the lungs located in the chest cavity. There, gas exchange occurs between the incoming air and the blood. Due to the fact that the animal's heart is shifted to the left, its right lung is slightly larger than its left.

A dog's breathing rate fluctuates over a wide range, depending on its condition, age, time of day, weather, physical activity, as well as breeds. Small dogs breathe noticeably more frequently than larger breeds. Thus, an adult Japanese Chin calm state breathes 22-25 times a minute, and the German Shepherd - 12-14 times. The appearance of a stranger in the dog’s field of vision can also lead to increased breathing.

Thanks to the circulatory system, blood is pumped with the help of the heart through blood vessels that permeate the entire body of the animal. Blood supplies the body with oxygen, nutrients, and frees it from waste products. Blood circulation is carried out through a closed system; the speed of complete blood circulation can range from 13 to 25 s.

The main organ of the system is the heart, located in the chest cavity and shifted to the left. The normal pulse of a healthy dog, corresponding to the heart rate, depends on the breed and can range from 70 to 110 beats per minute (the smaller the pet, the faster the heart beats). The pet's pulse value is determined by the femoral or brachial arteries.

Like other vertebrates, The nervous system of dogs is divided into central and peripheral. The central nervous system (CNS) includes the brain and spinal cord. The brain is the most important organ of the entire nervous system, controlling the functioning of the entire body. It processes information impulses sent by the senses and is responsible for coordination of movement, memory, emotions, etc. Placed in the skull.

Nerve cell: 1 - nerve cell body; 2 - core; 3 shoots; 4 - neuritis; 5 - the membrane forms, together with the neuritis, a nerve fiber; 6 - terminal branches of neuritis

The location of the spinal cord is the spinal canal. It originates from the brain and ends in the lumbar region. In this organ, nerve impulses are formed that are transmitted to the executive organs: muscles, blood vessels, etc. The reflexes of many motor reactions are closed on it.

The nervous system that is located outside the central nervous system is called peripheral. This system is responsible for coordinating movements, managing digestion, responding to danger or stress, or vice versa - optimizing the activity of the animal’s body during the rest period.

Excretory and reproductive

The organs of reproduction and excretion are closely related to each other. The male sex glands, the testes, are located in an external leathery sac called the scrotum. The sperm they produce enters the female's reproductive tract through the penis.

The female gonads, the ovaries, are located inside the body in the area of ​​the lumbar vertebrae. In addition to them, the female reproductive system includes the uterus, fallopian tubes, vagina, and external genitalia. The maturation of eggs in the ovaries occurs cyclically.

The stage of sexual arousal of the female manifests itself in the form of several processes: sexual heat, estrus, ovulation. Sexual heat is the positive reaction of a bitch to a male dog, the desire to get closer to him for sexual intercourse. Estrus externally represents the release of clear fluid from the female’s genitals. Ovulation is the release of a mature egg from the ovary.

Important! The first heat can occur when the bitch is not yet a year old, but this does not mean that she is ready for pregnancy, since the formation of the adult body is not complete and some organs are not developed. Therefore, it is usually recommended to make the first mating at the age of one and a half years.

The dog's excretory system consists of two kidneys connected by the ureters to the bladder. The kidneys, by filtering the blood, secrete urine, which accumulates in the bladder and is expelled through the urethra, which passes through the penis in males or the external genitalia in females.

Sense organs

A dog, like any predator, has well-developed senses. Each of these organs is arranged according to a single scheme: a receptor (perceives information from the outside), a conductor (transmits information to the brain) and a brain center (analyzes information and reacts to it).

As visual receptors The eyeballs protrude, connected by nerves to the brain. They are placed in the eye sockets and consist of several membranes containing vitreous. Dogs' vision is different from human vision.

These animals do not distinguish between red, orange, yellow and green, and they perceive everything blue and blue-green as white. But they perfectly distinguish shades of gray. In the dark they see much better than humans. Each dog's eye has its own field of vision. They notice even minor movements of objects well, but visual acuity in dogs is worse than in humans.

The ear as a receptor consists of the outer, middle and inner ear. The external one picks up sounds using the auricle. On average, sound is converted and transmitted to the inner ear. From the inner ear, the information received is transmitted through the auditory nerves to the brain.

Dogs hear over a much wider range than humans - from 12 Hz to 80,000 Hz, i.e. hear ultrasound. They can distinguish sounds of medium intensity at a distance of up to 50 meters (people up to 10 meters), and on a quiet night up to 150 meters.

Did you know? Long-term exposure to noise, including ultrasound, is poorly tolerated by dogs. Therefore, ultrasound is used not only in the training process, but also to scare away aggressive animals.

The receptors responsible for the sense of smell in dogs are located inside the nasal cavity. These are the endings of special nerve cells through which smell sensations are transmitted to the brain.

The dog’s olfactory organs: 1 - inferior turbinate; 2-superior turbinate; 3 - olfactory cavity; 4 - brain cavity

The layer of these cells, called epithelium, is significantly larger in area and thickness than in humans, so a dog’s sense of smell is an order of magnitude superior to a human’s. Pets can smell a scent from more than a kilometer away; they can distinguish up to a million different odors.

Taste buds, called taste buds, line your dog's tongue and mouth. Their endings transmit sensations to the brain. It is not known for certain how exactly a dog tastes different foods. But rewarding your pet with food has been successfully used in training for a long time.

In conclusion, we can say that by understanding at least the basic basics of a dog’s anatomy and physiology, the owner will have a much better understanding of his pet’s behavior and be aware of the problems that he may encounter. Ultimately, this will lead to better mutual understanding between the pet and its owner.

Video: Anatomy of dogs