Horse care

Anhidrosis is a fairly common problem for horses in hot and humid regions, but there is hope for keeping them in work, even without relocating.

BY SARAH E. COLEMAN

Anhidrosis is a condition defined by the decreased ability to sweat in response to an increased body temperature. It’s often thought to be intricately tied to high heat, but its occurrence is more selective: high temperatures must be in conjunction with high humidity.

This condition is cause for concern because between 65 and 70 percent of a horse’s body heat dissipates from sweating, so the inability to cool down can cause a significant impact on health.

SIGNS OF ANHIDROSIS Though horses with anhidrosis are often called “non-sweaters,” this term is misleading: The majority of horses with the condition suffer from incomplete or partial anhidrosis, meaning they don’t sweat as much as they should, or they sweat in abnormal patterns—not that they don’t sweat at all.

This condition is most often diagnosed in performance horses that are in work, but it can affect any horse, including those that are retired and not ridden. Studies have shown that darker-colored horses are often more affected by anhidrosis than their lighter-colored counterparts1 .

This condition doesn’t appear on most horse owners’ radar until their horse has a fairly serious health episode that is linked back to environmental conditions. As temperatures rise, horses suffering from anhidrosis may show a decrease in exercise tolerance and a higher-than-expected respiratory rate for the amount of exercise that was undertaken.