Anhidrosis in Equines


Summer comes with its perks, and animals tend to enjoy summer as much as they can. Summer means a lot of activity for the horses, especially. When your horse runs and does strenuous exercise in a hot environment, your horse produces heat because of muscle metabolism. To lower down the body temperature, raised because of metabolic heat, your horse produces sweat. Sweat production is normal and essential to keep the body temperature at its normal. However, if your horse cannot produce sweat, it becomes difficult to lower down the raised temperature. This condition is known as anhidrosis.


A horse with anhidrosis is often called a non-sweater. The inability to produce sweat can be partial or complete. Anhidrosis is the complete absence of the production of sweat. This condition results in the decreased performance in horses and poses a risk of hyperthermia or heat stroke. Anhidrosis is often observed in performance horses.


Horses who put a lot of effort into exercise develop this abnormality because of the over-stress put on the sweat glands. The degree of severity of anhidrosis varies among horses. Some horses produce less stress and suffer a lesser degree of hyperthermia, while some horses have a complete absence of sweat production and suffer a high degree of hyperthermia. Let us discuss how sweating occurs and how it plays its role in the normal physiology of your horse.

Why and how sweating occurs?
  • The working muscle of your horse produces heat that is the product of muscle energy metabolism.

  • This heat needs to be dissipated as early as possible.

  • The blood absorbs as much heat as it can and transport it to the lungs, where it goes away along with the exhaling breath. The exhalation dissipates some of the heat while the rest of the heat is dissipated through the skin.

  • Now, if the energy production is greater than the energy dissipation, your horse’s body temperature tends to rise.

  • The hypothalamus of the brain, when detects the rise in body temperature, signals the sweat glands to produce sweat. Sweat, consisting of water and electrolytes, helps a great deal to dissipate the extra energy.

  • If somehow sweat glands cannot produce sweat, your horse’s body temperature tends to rise. After a strenuous exercise, there is so much heat accumulation in the body that your horse becomes prone to severe heatstroke that may take its life.

What causes anhydrosis?

Anhidrosis often develops in areas of high temperature and humidity. The regions where temperature and humidity remain for longer periods put a great threat to horses. Anhidrosis mostly develops due to the overstimulation of sweat glands. When horses suffer high temperature and humidity stress, their hypothalamus in the brain signals the sweat glands to produce more and more sweat. The sweat glands become exhausted because of the overstimulation of beta-adrenergic receptors by stimulating hormones. This over-stimulation results in the failure of sweat production by sweat glands. It is not common that anhidrosis affects only a specific breed of horses. Anhydrosis can affect any horse of any breed, age, sex, or birthplace.


The overstimulation and exhaustion of sweat glands may result in less sweat production or no production at all. Anhidrosis mostly develops in horses that live in hot regions of the world. The owners identify their horses as not performing well in physical activities. Your horse’s activity may be greatly reduced, and your horse feels a lot of discomforts outside. Your horse may respire more than other horses, and his temperature rises far more than normal. As an owner, you can easily detect these signs and start immediate actions against them.


What are the symptoms of anhidrosis?

Identifying a horse suffering from anhidrosis is not so difficult. You can easily spot an anhidrotic horse by observing. An anhidrotic horse will show a slower gait, heated up the skin, clear bald patches on it. In extreme cases, when an anhidrotic horse completely loses the ability to sweat, its skin gets dry. Therefore, the condition is often called a dry coat or dry horse.


Most of the time, when an anhidrotic horse is presented to a veterinarian, the owners often complain about the performance issues. As an owner, you should understand that performance issues, high body temperature, and slower gait can mimic the condition of an infected horse. If your horse gets an infection, he can show the signs of an anhidrotic horse. Therefore, you should make a difference among these conditions or let your vet make this differential diagnosis for you.


Other signs and symptoms that your anhidrotic horse can express are as follows.

  • Loss of appetite

  • Reduction of water intake

  • Dry, hot coat

  • Clear bald patches on the skin, facial hair loss

  • Decreased activity, lethargy, and exhaustion

  • High respiration rate, labored breathing

How can anhydrosis be controlled?

There is no obvious medical treatment for anhidrosis in horses. Only treatments that exist are supporting ones, but they have shown significant results. The all-time famous treatment of anhidrosis is letting your horse spend almost half an hour in cool water after exercise for 30 days. This method has shown significant relief to horses. You can also move your horse to a relatively cooler region of the world. Besides this, the administration of vitamins and minerals to your horse can also positively treat anhidrosis. Recent studies (Including one from the University of Florida Vet Med School) show that holistic therapies such as acupuncture and herbal medicines can greatly increase the ability to produce sweat in anhidrotic horses. In my opinion, you should not stick to only one of the treatments; instead, you should try whatever makes your horse feel good and healthy.

Final thoughts

Anhidrotic is not a disease; instead, it is an abnormal condition developed due to stress. Therefore, a conventional line of treatment is not helpful in this condition. You need to eliminate the cause of anhidrosis first; then, you should try to calm your horse and decrease the stress as much as you can. Only then the supportive treatment or the holistic medicinal approach can do their wonders and make your horse healthy and fit.


Trying acupressure for your horse could be a great supportive option. Acupressure supports the body and encourages it to produce sweat naturally. Practitioners use specific points (acu-points) along the body to stimulate certain aspects of the body. Continual sessions can show improvements for your horse. Acupressure is great complementary care. So, you can always add acupressure sessions to help support your horse.


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