22/06/2025
Heatstroke in Horses
Outdoor riding is at the top of everyone’s list during summer, but beware the effects of hot weather on you and your equine companion. When temperature rise into the 40s and 50s, the effects of hot weather can become life-threatening, especially when exercising.
Heatstroke is is life-threatening emergency where the body temperature rises to dangerous levels. Signs include elevated re**al temperature (above 106°F), rapid breathing and heart rate, distress, dehydration, weakness, in-coordination, and potentially collapse. If a horse shows these signs, immediate cooling measures and veterinary care are crucial.
Extreme heat can lead to dehydration, tying up, heat exhaustion, colic and even death.
Horses produce large amounts of heat via digestions and muscular activity. Typically, when the air is cooler than body temperature, blood is shunted to the skin to remove excess heat; however, if the air temperature is warmer than body temperature, sweating becomes the primary means of heat loss. Horses and humans are the only mammals that cool via sweating. Sweat wets the body and cooling occurs by evaporation. During hot and humid weather, sweat does not evaporate and adequate cooling does not occur, leading to heat exhaustion or to life-threatening heat stroke.
Symptoms of heat exhaustion include:
• Profuse sweating or less sweat than expected.
• Hot skin (might progress to cold if skin circulation shuts down).
• Muscle weakness or stiff and reluctant to move. The horse may be experiencing rhabdomyolysis. Call your veterinarian.
• Stumbling and loss of coordination
• Rapid breathing. (Normal breathing rate for an adult horse is 8-20 breaths per minute.) Call a veterinarian if the rate is over 40 bpm. Ahsan Razzaq 0300 7939482
• Rapid heart and pulse rates that don't recover after exercise. A sustained heart rate of 80 bpm warrants an emergency veterinary visit.
• Increased body temperature of 102 degrees to 106 degrees F. (Normal temperature is 98-100.5 degrees F.) Heat stroke occurs above 106 degrees.
• Signs of dehydration, including loss of skin elasticity, sunken eyes, tacky membranes and cessation of urination.
• Collapse may occur in severe cases, and the horse can become unresponsive.
If heat exhaustion is not treated and the horse experiences heat stroke, the horse may collapse, convulse, and die.
If a horse becomes overheated, stop riding the horse immediately. Call a veterinarian; the situation may become an emergency. Place then horse under a fan and hose off with cold water, concentrating on areas with large vessels, such as inside the thighs. A sheet can be soaked in ice cold water and then put over the horse to encourage cooling. The horse will likely require electrolyte supplementation and intravenous fluids for circulatory shock. A veterinarian can administer various noninflammatory medications.
The prognosis for heat exhaustion is generally good, but for heat stroke, the prognosis is guarded to poor, especially if the horse has collapsed and gone into convulsions.
It is best to prevent heat stress by acclimating the horse to the climate, riding early in the morning or evening, and monitoring for dehydration, which might darken and concentrate the urine. Horses with long hair coats should be clipped. Calculating the heat index may alert the horse owner to unfavorable weather conditions where the horse should not be worked.
To calculate the heat index, add the temperature in Fahrenheit and the percentage of relative humidity. When the index approaches 130, use caution and be sure your horse has plenty of water. When the heat index approaches 180, the horse should not be exercised, as the horse will not be able to cool adequately.
Horses at risk for heat stress include poorly conditioned and overweight horses, geriatric horses, horses in direct sunlight in temperatures above 95 degrees F, horses in hot poorly ventilated stalls or trailers, and horses no acclimated to hot weather. Horses that do not consume enough water and electrolytes are also at risk.
Guidelines
• Provide free access to palatable water.
• During exercise, allow the horse to drink as often as possible.
• Provide salt to encourage adequate water consumption and help maintain electrolyte balance.
• A powdered electrolyte is a good choice to use when adding electrolytes to the feed. A mixture of table salt and lite salt in equal amounts may be used.
• Give your horse free access to salt even when using electrolytes.
• It cannot be over-emphasized to supply sufficient water any time you give electrolytes.
Any stress can lead to gastric ulceration, including heat and travel. Some horses with gastric ulcers will consume less water, placing them at a higher risk for heat stress.
Enjoy the summer weather and your horses, but use caution when the heat becomes extreme.
Hoof and Paw Veterinary Hospital
