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Equine Health Resource

Heat Exhaustion or Stroke

Synonyms: Hyperthermia, Sunstroke

Horses primarily cool themselves by sweating. Although horses can “pant” through their nose, this is a much less effective means of dissipating heat.

Prolonged exercise or exposure to hot conditions can result in dehydration, heat exhaustion or heat stroke. This is particularly true in humid conditions, because the humidity inhibits sweat from evaporating off the skin’s surface.

“Exhaustion” or “Stroke”? The difference in terminology is a matter of degree, not kind. Heat exhaustion is characterized by dehydration and overheating that may be reversible with prompt treatment. Heat stroke implies something more severe, and is characterized by total collapse, as a horse is in imminent danger of dying. A normal rectal temperature for horses ranges from 98 – 101 degrees.

Generally, a horse is in danger of developing heat exhaustion or stroke if their rectal temperature rises above 104 degrees. The higher the temperature, the more aggressive the treatment that is needed.


  • How severely affected is my horse?

    Avoid prolonged exercise is hot or humid conditions. Consider bathing a horse before exercise, and after. Do not exercise a horse beyond their fitness level. Gradually warm up and cool down your horse before and after exercise. Take regular breaks and ensure that your horse is well hydrated at all times. Monitor your horse's vital signs. Consider your horse's coat length and thickness. If it is thick and long, it may inhibit cooling and you may want to consider clipping.
    Author: Doug Thal DVM Dipl. ABVP


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