Anhidrosis: Decreased or Inability to Sweat

Dr Caity Cosentino

It’s the middle of summer and outside is a sauna. You would expect your horses to be sweating as much, if not more than you are, but what if one of them is not? You notice that after your ride, there is barely any sweat under your saddle pad and your very fit horse is breathing heavily after what was only a light hack. He may be suffering from a condition called anhidrosis. Anhidrosis is not a common affliction, but can be a frustrating problem to deal with, especially in the competition horse. Horses, like humans, sweat to help moderate and regulate their body temperatures. Without the ability (or a decreased ability) to sweat, the horse will become overheated, have labored breathing, an increased heart rate, and become fatigued more quickly. If pushed too hard a horse suffering from anhidrosis may even collapse. A horse who has had the condition chronically may also have a poor hair coat and dry skin.

Horses most commonly effected by anhidrosis live in hot, humid climates, but any horse may be effected by this condition. Horses who are dark in color also tend to be more prone to developing it. There is no way to predict what horses will or will not develop the condition. If your horse has been diagnosed, it is important to keep them as cool as possible, especially in the heat of the day. Having them inside with a fan or at least making sure they have access to a shady run-in is crucial. Providing clean cool water at all times and supplementing electrolytes in the summer months will help your horse stay hydrated. Riding only early in the morning or later in the evening, when temperatures have cooled off, will help by putting less strain on their bodies during work. Regular grooming to help keep a healthy coat will make them more comfortable as well.

Some horses who abruptly stop sweating will just as abruptly start sweating again. It is unknown why these horses are affected, but you should consult with your veterinarian to come up with the best treatment plan for your horse. There is no specific cure for anhidrosis, but there are supplements and therapies that have proven to help some individuals regulate their temperatures and begin sweating again. Even though anhidrosis is an obscure problem, effecting only about 2% of horses according to research, it is a good condition to keep on your radar, especially if you have a horse who isn’t competing at the top of his game and may not be sweating appropriately.

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