What is the condition called where some horses do not sweat, especially in excessive heat?

Anhidrosis is the condition characterized by the inability of some horses to sweat, particularly in hot and humid conditions. In healthy horses, sweating is a crucial physiological response that helps regulate body temperature. When a horse suffers from anhidrosis, it cannot produce sweat effectively, which can lead to overheating and other heat-related issues.

This condition can be especially problematic in warm climates or during periods of high heat, as the horse's body temperature can rise dangerously. Anhidrosis can occur due to various factors including breed predisposition, age, or environmental factors, and recognizing it is essential for the welfare of the horse.

While hypohidrosis also refers to reduced sweating, it is generally used to describe an incomplete ability to sweat rather than a total inability, making anhidrosis a more precise term for the complete lack of perspiration. Heatstroke and hyperthermia pertain to heat-related illnesses due to excessive body temperatures but do not specifically describe the lack of sweating itself.