They might be on opposite ends of the spectrum, but hyperthermia and hypothermia in horses are more alike than one might think. At the 2013 Western Veterinary Conference, held Feb. 17-21 in Las Vegas, Nev., Amelia S. Munsterman, DVM, MS, Dipl. ACVS, ACVECC, reviewed these two equine environmental emergencies and how to best manage affected horses.

Munsterman, a clinical lecturer in equine emergency and critical care at the Auburn University College of Veterinary Medicine, explained that both conditions result from circumstances that overwhelm horses’ normal thermoregulatory mechanisms.

“Both conditions result in an aberrant core temperature, accompanied by an exaggerated acute phase inflammatory response and multi-organ failure,” she said.

She noted that several factors can predispose a horse to developing hyperthermia and hypothermia, including:

  • Age;
  • Illness;
  • Metabolic disorders;
  • Injury;
  • Electrolyte imbalances; and
  • Lack of acclimatization in a new climate.

Munsterman reviewed each condition and described treatment options for a veterinary audience.


By definition, hyperthermia describes a core body temperature that exceeds a horse’s thermoregulatory set point; essentially, it’s an elevated body temperature. Extreme hyperthermia is referred to as heat stroke, Munsterman said, and occurs when the horse’s body temperature rises to about 105.8°F. In compromised horses, she noted, the temperature at which an animal develops heat stroke can be lower. A combination of heat and humidity can place horses at risk f