Anhydrosis The horse is the only mammal, other than humans, that cools himself by sweating. Once internal body temperature rises to above 105^oF, heat stroke and other thermal-related injuries become an issue. The inability to sweat in response to work and/or body temperature increases is called anhydrosis. Horses with this affliction are also referred to as dry coated, puffers, or non-sweaters. It is estimated that 20% - 30% of horses in southern regions are anhydrotic to some degree. Usually the first sign of a problem with a shy sweater is a decrease in the level of performance, possibly with some panting. Signs of an anhydrotic horse: 1. Inability to sweat. 2. Increased heart rate. 3. Increased respiratory rate. 4. Higher body temperature (as high as 108^oF). 5. Decreased tolerance for exercise. 6. Panting is also a common sign. 7. Hair loss. 8. Dull, rough hair coat. 9. Skin becomes dry, flaky, and itchy. In hot weather, always ensure that there is an ample supply of water, to allow conversion of moisture within the body for perspiration. In extremely hot and humid conditions, you can help to cool a horse, anhydrotic or not, by using a misting machine. There are some nutritional factors that seem to apply to these horses as well. They sometimes exhibit an electrolyte imbalance. Low amounts of sodium, chloride, and potassium are found in the diet, and this can be easily remedied. It is common to find that anhydrotic horses suffer from hyponatremia (low sodium levels in the blood) and hypochloremia (low chloride levels in the blood). Unfortunately, electrolyte supplementation does not help all of these horses, and prophylactic use doesn't seem to make a difference. There has also been some relief seen with the administration of thyroxine and casein, but again, with no consistency. To date, the best and most consistent results are achieved by sending these horses into cooler climates. To continue to exercise them as non-sweaters is taking a huge risk, inviting heat stroke and death. Until a definite cause and cure can be found, careful management is the only thing that can be done.

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