Anhydrosis- a Heated Issue

updated at: Tue 08 Aug 2017




It’s summer time in the Northern Hemisphere, which means the mercury is rising and the sun is shining! All in all, it’s a wonderful time of year- or at least it should be. For horses with Anhydrosis, it can spell disaster. While we associate the hot weather with fun and games, horses afflicted with Anhydrosis feel nothing but discomfort and stress. While we can’t exactly turn off the sun, there are other ways we can manage the comfort of our equine friends with this condition.

What is Anhydrosis?


A horse that is puffing for prolonged periods of time after exercise instead of sweating may have Anhydrosis.

Anhydrosis is a condition that does not discriminate between breed, age, sex or color. Also known as dry horse syndrome or the puffs, it is defined as the inability to sweat effectively in response to appropriate stimuli. Put simply, the horses sweat glands simply give up. 

Normally, horses can expel up to 65% of their body heat through evaporation of their sweat, so horses that are unable to do this greatly risk overheating. 

Anhydrotic horses can also suffer prolonged periods of elevated pulse and respiratory rate after exercising as they try to cool themselves through puffing. In unaffected horses, respiration would only account for 25% of heat loss. Regularly, the process of a horse returning to normal body temperature takes no more than 30 minutes.

There are varying degrees of Anhydrosis, the most common being what is classified as incomplete. Horses may live for many months without diagnosis in this situation as the symptoms do not present themselves often or to the severity that chronic and acute cases do. This may simply be because the horse may not be under the stress of intense exercise at any given point in time.


Symptoms of Anhydrosis

Symptoms that may be indicative of Anhydrosis may include;

  • Inability to sweat after exercise
  • Significant and prolonged puffing
  • A dull and dry coat
  • Loss of patches of hair on the face
  • A particularly lethargic and intolerant attitude towards exercise, particularly when it coincides with hotter weather. 

Some horses have also been known to sweat profusely for weeks or days before they come down with Anhydrosis.
If your horse has an incomplete case of Anhydrosis, it may not exhibit all or any of these symptoms. However, if your horse suddenly has a drastic change in performance or is resistant to activities they would normally enjoy when the climate is hot and humid, it might be worth investigating the Anhydrosis route.



What causes Anhydrosis?


There is no known cause for Anhydrosis, and its onset can be slow or sudden. What we do know is that it is typically seen when a horse is moved to, or lives in, a hot and humid climate. We also know that the sweat glands of the horse become unresponsive and cease working. 

There are many theories surrounding the cause of Anhydrosis, one of which is related to the horses diet. It is thought that perhaps nutrient rich diets, especially those high in carbohydrates, may cause hormonal imbalance and metabolic heat production. This metabolic heat production (the heat created from the digestion of food) may be affecting insulin and cortisol levels which eventually comprise the horses inability to sweat.

How to manage Anhydrosis

If we prescribe to the above theory, then feeding a low NSC diet should help to manage those horses with Anhydrosis. Stance customers have had success feeding CoolStance to Anhydrotic horses, as shown in the preview of a testimonial from Terese and her horse Abbey below (before pic above, after pic below);

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