How is the circulatory system of a horse


In the article of Today we tell you about one of the fundamental parts for any living being: the circulatory system. And specifically that of equines.

Biologists who are experts in these animals state that approximately 300 different breeds of horses can be found. Each breed has its particular characteristics both in the external appearance of the animal, however in terms of the functioning of the body all equines develop and work in a practically identical way by belonging to the same species of the animal world. Therefore, in terms of their circulatory system, regardless of the breed, what you can discover in the article is applicable to all horses, whatever their breed.

Do we know a little better this part of the body of these incredible animals?

The functioning of the circulatory system is very similar both to humans and to other mammals. ANDThe circulatory system is made up of the cardiovascular system, formed by the heart and the conduits through which the blood circulates, and by the lymphatic system. The fundamental organ of the circulatory system is therefore the heart, which is in charge of pumping blood to all parts of the body through veins, arteries and capillaries. On the other hand, the lymphatic system is formed by the lymphatic vessels, by the lymph nodes and two organs: the spleen and the thymus. It is in charge of the immune system of the mammalian organism.

circulatory system of a horse

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The cardicovascular system

This system is in charge of channeling and propelling the blood so that it irrigates the entire body. A medium-sized adult horse has about 9 liters of blood in his body. Blood is essential as a transporter of vital substances for the body such as: food, oxygen, cells of the immune system, etc. And it also helps purify the body by transporting waste or carbon dioxide. As if this were not enough, it is also in charge of regulating body temperature.

This system It has two circuits, one is responsible for covering the area of ​​the lungs and the other carries the blood to the rest of the body. Both circuits are circular, beginning and ending in the heart.

These circuits present the pattern in terms of the places through which the blood passes: heart, arteries, arterioles, capillary network, venules, veins and heart.

El pulmonary circuit is responsible for making the gas exchange carried out in the lungs. Blood circulation in the lung area plays a fundamental role in nourishing the structural components of the lungs, rebuilding the lung tissue and distributing the oxygen taken up by the body.

The heart

The heart is made up of muscular tissues and represents a more rounded shape in the case of the human being. The heart of an adult horse can weigh about 3,5 kg. As in the rest of mammals, the heart of horses consists of four cavities: two ventricles, which are the ones that propel blood, and two atria, one of which collects blood from the lungs and the other from the rest of the body.

The heart is arranged between the second and sixth intercostal space in equines.

We have talked about various types of ducts present in the circulatory system, we are going to look at them now with a little more attention individually.


They are conduits that carry blood from the heart to other organs in the body. They are thick tubes since they must withstand the blood pressure caused by the pumping of the heart. Within the arteries there are different classifications that we will only name in this article, and they are: large or elastic, medium or muscular, and small or arterioles.


Capillaries are very small diameter blood vessels. In them, an exchange of molecules takes place between the cells of the tissues and the blood.. They are arranged in groups called vascular networks, which are very extensive and cover all organs.


They have a very similar structure to that of arteries and are also classified according to their size into: large veins, medium veins and venules or small veins. Medium veins, which are approximately 10 mm in size, are the most abundant.

The veins They are responsible for carrying the blood from the blood capillaries to the heart. Are those that they generally transport waste and carbon dioxide. There are some exceptions such as the pulmonary vein that conduct oxygen to distribute it.

The lymphatic system

Lymphatic ducts carry lymph, a liquid that is collected in tissues and organs throughout the body and deposited in large veins.

The lymphatic system is the in charge of maintaining fluid balance by draining excess interstitial fluid to blood, is also responsible for immunity to act as a filter against different germs that enter the body and thus ensuring the body's immune defense. It also helps the cardiovascular system by control venous and arterial blood pressure.

If this system malfunctions or deteriorates, the lymphatic disease called lymphangitis appears.

Lifangitis can be ulcerative (bacterial infectious disease) or epizootic (fungal infectious disease).

Two fundamental organs come into play in the lymphatic system: the spleen and the thymus. Of which we want to tell a little more.


It is the largest lymphatic organ and is the in charge of immune and hematopoietic functions. Strongly irrigated by the blood system, it removes damaged red blood cells from circulation and holds blood cells together.


This bilobed organ, located near the heart, is supplied by blood vessels. Has his main function from birth to puberty and is where T lymphocytes mature.

Finally, we want to dedicate a small section to the importance of the clinical examination of our horses, since Although cardiac lesions in them do not manifest as much as in other mammalian species, there are many and important lesions that must be diagnosed correctly. Therefore, it is recommended that a professional check our horse from time to time.

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