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Horse Heat Index Graphic

It’s summer! Time for cookouts, beaches, vacations, and of course, riding. Horse show season is in full swing. The days are long and the hot weather is moving in. We know our horses can overheat in summer conditions, but how much is too much? As the temperature and humidity rise, we need to be vigilant about protecting our equine friends from heat stress.

The horse heat index

This is a good time to revisit the Horse Heat Index. This index has been around in one form or another for years and provides good general guidelines for working your horse. We like it because it’s easy to use, and you don’t need a calculator.

To use the index, all you need to do is add the current temperature (in Fahrenheit) and the relative humidity (in % RH) together. The total number determines the conditions. For example, if it is 77 degrees out and the relative humidity is 65 %, add them together for a total of 142. When you have your total, see the table below for recommendations.

Keep in mind that, as with us riders, all horses are different. Some handle heat better than others, so always watch your horse for signs of heat stress.

If Temp °F + % Relative Humidity =

120 or less Your horse’s cooling system is functioning very effectively. You are safe to do all the riding and training you like with no real worries.
120-150 Cooling efficiency is decreasing through this range. Horses will sweat up with work, so make sure they have a chance to rest and cool off over the course of a long ride or heavy work.
150-180 A horse’s ability to regulate its temperature is greatly reduced and heat stress is more likely, so be careful. Stick with light work and keep watch for signs of overheating. Make sure to cool your horse down properly afterwards.
180 or more Your horse has lost the ability to regulate its temperature. Over-working a horse in these conditions can be dangerous, even fatal. Do your horse (and yourself) a favor and take the day off!!


Signs of heat stress

These are some of the signs of heat stress in your horse. If you see any of these symptoms, get immediate veterinary help for your horse.

  • Restlessness, lethargy or depression
  • A heart rate of 80 or more that does not return to normal after several minutes of rest
  • An erratic heart beat
  • A respiratory rate of 30 or more that does not return to normal after several minutes of rest
  • Sweating that is either excessive or ceases altogether
  • Body temperature in excess of 103 °Fahrenheit that does not decrease with several minutes of rest
  • Excessive salivation or redness of the tongue and mouth area
  • Muscle spasms, stumbling gait or collapse

We all love and value our equine partners. An eye on the weather and a little simple math can help us keep our horses and ourselves healthy in the summer heat. Enjoy your summer, and Happy Trails from your friends at Equus Athletics, home of the original EQUISTIX Equine Sports Massage Therapy Tool.

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