Anatomical And Physiological Foundations Of The Exterior And Constitution Of Horses

Anatomical And Physiological Foundations Of The Exterior And Constitution Of Horses
Anatomical And Physiological Foundations Of The Exterior And Constitution Of Horses

Video: Anatomical And Physiological Foundations Of The Exterior And Constitution Of Horses

Video: Anatomical And Physiological Foundations Of The Exterior And Constitution Of Horses
Video: Topic 1a Foundations: Introduction to Anatomy- Dr. Basu's Easy Anatomy & Physiology Lecture 2024, March
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The external forms of a horse depend on the anatomical, histological and physiological properties of its body. When studying the exterior of a horse, it is especially important to know the systems of the organs of movement, the skin, digestion, gas exchange and blood circulation.

Horse skeleton. The bones of a horse are distinguished by a more powerful development in length and thickness, a denser structure and greater strength than the awn of other less mobile animals. The bones of the lower, distal parts of its limbs are especially long in a horse. Longer and thinner bones of the limbs in horses with fast gaits. In stepping horses, they are shorter and thicker. This provides horses with fast gaits with greater grip and greater thrust power for stepping horses.

Horses have better musculature than other farm animals. Strength depends on the mass of muscles, and the nature of work depends on their shape. Horses with fast gaits have dense muscles made up of long, slender muscles. Stepping horses, on the other hand, have looser, flatter muscles, consisting of short and thick muscles. The long and slender muscles of fast-paced horses are capable of greater contraction, but do not exhibit great strength. On the other hand, short and thick muscles of heavy trucks, on the contrary, contracting a little in length, provide them with great strength.

Red-haired horse frolics in the meadow, photo photography
Red-haired horse frolics in the meadow, photo photography

Tendons and ligaments, especially on the limbs, are much better developed in the horse than in other domestic animals.

Leatherthe horse is thinner than that of cattle and pigs, but thicker than that of sheep. Its development depends on the age, constitution, breed, climate, conditions of keeping and use of the horse. Foals have thinner skin than older horses. The more fast-paced work a horse does, the thinner its skin. Thin skin facilitates heat transfer by evaporation of sweat through it and blood circulation in the superficial blood vessels. Horses from areas with cold climates have thicker and denser skin with a thick, long and matte coat that grows back strongly in winter, three of which its surface is relatively smaller than that of southern and fast-paced horses. In the latter, the skin is also thinner and more delicate, with short, thin and shiny hair. These horses have a pronounced network of blood vessels and well-defined "repulsed" tendons.

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Compared to other farm animals, the horse's sweat glands are larger. No animal sweats as much as a horse. Sweat first comes out on the sides, then on the shoulders and on the neck; finally, she sweats all over her body and becomes all wet, "covered in soap."

Hair. In the scalp of the horse's skin, four types of hair are distinguished: protective (bangs, mane, tail, brushes), integumentary (throughout the body), down (growing in winter) and tactile (around the eyes, nostrils and lips).

Chestnuts, spurs. These horny formations of skin on the limbs of a horse are rudiments of the crumbs of its semi-descending ancestors. There are more chestnuts and spurs in horses with thick skin and a large coat than in horses with thin skin and little coat. Sometimes chestnuts are absent on the hind legs of horses (as in donkeys and zebras).

The digestive organs. A horse adapted to an active lifestyle, in comparison with other hoofed herbivores, has less voluminous digestive organs: a narrow, long esophagus, a single-chamber stomach and short intestines. Accordingly, the horse has especially developed jaws, chewing muscles, teeth, lips and tongue for better gripping and chewing of dry food.

Horse skeleton, diagram drawing
Horse skeleton, diagram drawing

Respiratory system. Due to the special arrangement of the palatine curtain, which separates the oral cavity from the respiratory tract, the horse breathes only through the nose. The horse's nasal cavity has a very large capacity, and the mucous membrane of the cavity is very richly supplied with blood vessels and endings of the olfactory nerve. In the nasal cavity, the inhaled air is cleaned of impurities and warmed up. Particularly mobile pterygoid cartilage (snoring) of the nostrils serve to regulate (expand and narrow) their lumen.

In the area of the horse's larynx, the vocal cords are located, the vibration of which causes neighing. The retraction of the arytenoid cartilage of tartan also causes a respiratory defect - wheezing, or rorer. At rest, this defect is not noticeable and is detected only during and after movement with hoarse breathing. Irritation of the larynx by squeezing with the hand - can force the manifestation of the defect. Usually, wheezing in a horse is easy to detect when it moves uphill at a trot or gallop, or when jumping over obstacles. The predisposition to whistling suffocation is hereditary.

The horse's lungs weigh 4.5-6.5 kg, their capacity at rest is 40-45 liters. Horses with striding gaits have less lung weight and capacity in relation to the weight of the animal than fast-paced horses.

Breath. In a calm state, the number of respiratory movements in a horse ranges from 8 to 16 times per minute. For fast-paced horses at rest, fewer respiratory movements are characteristic than for horses with striding gaits. The horse has very large respiratory reserves and uses them during work. A well-trained horse with "open breathing" is capable of increasing the capacity of its lungs by 2-3 times during work, the breathing rate by 5-7 times and pulmonary ventilation by 10-12 times. However, the body's need for oxygen during fast movements can increase 15-16 times. In such cases, the horse feels a lack of oxygen and has a so-called oxygen debt, which is one of the main physiological reasons for its fatigue; horse fatigue is usually accompanied by slow, shortened and fuzzy limb movements. Horses with fast gaits show a great ability to increase the capacity of inspiration and the intensity of gas exchange during movement. Increased respiratory function in horses results in frequent colds and a special respiratory defect - fuse, or emphysema. This defect is a chronic dyspnea at rest, expressed in rapid and intermittent (in two jolts) breathing, noticeable by the movement of sighs, with a firing chute behind the last rib and along wide open nostrils. Such difficulty breathing is caused by pathological changes in the lungs, the alveoli of which have expanded, and the lung tissue has lost its elasticity and the ability to contract normally. Horses with a fuse cough, sweat and lose weight. This unresponsive breathing defect is caused by overloading of movement or by overexposing hot horses.

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Circulatory organs. The horse's heart, located in the chest cavity between the third and seventh ribs, is larger in size than the heart of other farm animals. Its average weight is 3.5-4.5 kg, its average capacity is 4.5 liters. Some horses, for example the thoroughbred horses Eclipse and Budynok, had a very large heart, weighing up to 7-8 kg. The absolute weight and capacity of the heart in horses with fast gaits is usually less than in walking horses, but per 100 kg of live weight in fast gait horses there is a relatively higher weight of the heart and a relatively large heart capacity.

Horse musculature
Horse musculature

Circulation. In the normal and calm state of the horse, the number of heartbeats, or beats of its pulse per minute, is 36-44. Young horses have a faster heart rate than older horses. Horses with fast resting gaits usually have a lower heart rate than steppers. With accelerated movements, at work, with nervous excitement and an increase in temperature, the horse's pulse rate increases to 120-130 per minute. A horse's heart rate is an important clinical indicator of its health, fitness, tension and fatigue from work. By the increase in the pulse after the tests, as well as by the speed of its return to normal, the readiness and working capacity of the horse are judged.

The horse's cardiovascular system has very large reserves, which, with sufficient training, are well utilized at fast paces. This can be seen from the following comparisons.

The amount of circulating blood per 100 kg of live weight:

at rest - 7.5 liters, in motion - up to 10 liters.

The amount of blood passing through the heart per minute, or the minute capacity of the heart:

at rest - 15-20 liters, in motion - up to 150 liters, that is, 10 times more.

An increase in blood circulation in a horse at fast gaits occurs due to an increase in the pulse rate, its impact force and the attraction of reserve blood reserves from the internal organs and body tissues to the cardiovascular system.

The blood of horses of fast paces of southern origin usually contains more erythrocytes, hemoglobin, and dry matter than in the blood of heavy draft horses of western origin. However, the composition of a horse's blood varies greatly from many reasons: from health status, age, sex, feed, nervous and muscular activity, sexual status, fertility, season and some other reasons. Therefore, hasty zootechnical conclusions should never be made on blood counts.

Two horses, photo photography
Two horses, photo photography

Body temperature. The horse, as a warm-blooded animal with the ability to regulate heat, maintains almost the same body temperature in every climate and season of the year. The temperature inside the body is higher than on the periphery. Extremity temperature drops progressively with distance from the body. The normal rectal temperature of adult horses ranges from 37.5 to 38.5 ° C. Young horses tend to have a slightly higher temperature than older horses. The morning temperature of the horses is lower than the evening temperature. Horses' temperatures vary depending on their diet, activity and health. The old division of horses into warm-blooded and cold-blooded, introduced into German zootechnical literature and practice by G. Natusius, is not confirmed by the actual temperature of horses. The body temperature of stepper horses is often higher than that of fast-paced horses.

The horse has an increased ability to regulate heat through sweating compared to a less mobile donkey that is unable to sweat much. And this is very important for the horse, since due to the increased evaporation of sweat from the skin surface, the excess heat generated in its body during fast movement and rapid breathing is released. If the horse did not have an increased ability to sweat, then when running, its temperature could rise to 42-43 ° C, which is fatal for it.

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Vision. The wild horse is farsighted. The domestic horse, on the other hand, is myopic and does not see well at a distance of more than 500 m. The domestic horse's myopia is the reason for its fearfulness. However, thanks to the eyes set to the sides, the mobility of the head and neck, the horse can easily view the surroundings around him in almost 360 °. The horse's eye is capable of perceiving a large number of light rays, distinguishes shapes, colors and the smallest details even at night, in the dark.

Hearing in a horse is better developed than sight. Like all non-arctic females, the horse has special air-filled supraglottic sacs connected to the nasal cavity and ear and possibly contributing to the clarity of its hearing. The horse's hearing is very subtle and acute, much better than that of humans. The horse perceives and distinguishes the smallest rustles and ultra quiet sounds.

The ears of the horse are very mobile, and he always listens. By hearing she recognizes the voice, even the gait of her groom. The horse easily develops auditory reflexes, and it easily learns to execute a command, even distinguishing the tone of voice. From the trainer's voice raising, the horse's heart rate increases.

The sense of the horse is very developed. The horse is very sensitive to sensations with the entire surface of his skin and especially with his lips and hooves. The sense of touch is the basis for controlling a horse, stroking it, as a pleasant reward for it, for example, after a correct jump.

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