Equine Anhidrosis
Horses with anhidrosis should be sheltered in hot weather.


Horses with anhidrosis should be sheltered in hot weather.

Anhidrosis is a mysterious disease affecting thousands of horses worldwide. Commonly referred to as dry coat, a horse suffering from anhidrosis has issues sweating to keep cool. Although there’s no cure for the condition, it can be managed.

Why horses have difficulty sweating
Research has yet to identify what causes anhidrosis, although it has disproved the once-common theory that the condition stemmed from a horse’s inability to adjust to hot weather. According to the American Association of Equine Practitioners, a study of Florida horses found anhidrosis was most common in the native population. Now, veterinarians and researchers suspect anhidrosis is a symptom of sweat glands that have been desensitized from an excess of neurotransmitters called catecholamines.

Regardless of its cause, anhidrosis is a serious condition. Your horse won’t be able to cool easily, especially in warm climates or after exercise, as the evaporation of sweat removes up to 65 percent the heat a horse generates through physical activity. If her temperature remains consistently high – from 106 to 110 degrees Fahrenheit – she could suffer from heatstroke. 

Symptoms of anhidrosis
An inability to sweat is the most obvious indicator of the condition, but it’s not the only one. Horses suffering from anhidrosis might simply sweat less than normal or only stop sweating in a particular area. Other symptoms include increased heart rate or body temperature, flared nostrils, labored breathing and difficulty working in hot climates. In extreme cases, the horse might collapse or suffer heat stroke. Horses with chronic anhidrosis often drink more water than normal, urinate frequently and have a reduced appetite. They might also develop skin and coat issues such as dryness and balding.

Not all horses react to the condition in the same way, so be on the lookout for any of these symptoms.


A veterinarian can help you diagnose your horse by injecting a small amount of terbutaline, a drug that stimulates the sweat glands, under the skin. Horses with anhidrosis are unaffected by the drug. Your vet will then develop a comprehensive treatment plan, but there are steps you can take if you notice symptoms. Adding a feed supplement with the necessary equine electrolytes – including salt, potassium, calcium, zinc and others – supports a horse’s ability to maintain a proper electrolyte balance and remain hydrated.

As Kentucky Equine Research pointed out, adding electrolytes is just one part of managing anhidrosis. In addition, you should keep your horse in a cool environment, especially during the day. Fans, air conditioning and water misters all help your horse from getting overheated. Make sure your horse has fresh, cool water throughout the day, and schedule exercise and turnout for the evening and night when temperatures are lower.

Before exercising, splash your horse with water to dampen her coat. Keep an eye on her breathing, and make sure there’s plenty of time for her to cool down afterwards. In addition, you should keep her coat trimmed and groomed to keep her skin cool. Regular grooming stimulates blood flow, bringing essential nutrients to the skin and sweat glands. 

Some veterinarians, according to the AAEP, have tried acupuncture to stimulate the sweat glands. No official study on acupuncture treatment has been conducted, however, and it’s unknown how long the effects can last.

If you suspect your horse has anhidrosis please consult with a veterinarian for diagnosis and management.



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