Heat Exhaustion in Horses

Summer time is here and with it comes risk of overheating, heat exhaustion, or heat cramps for horses especially performance horses.  The following situation comes from Nutrena Equine Specialist Jolene Wright, who owns and trains roping and barrel racing horses in Texas.

The temperatures had just started to get into the upper 90’s and I went out for my usual routine ride on one of my horses in training. I noticed after my ride and cooling him out that he began to get down and roll an hour or so after turning him back out and he was sweating. I had sprayed him off and cooled him out as usual, so I first thought colic since he was dropping down on the ground. As I got closer to his pen I saw his respiration was faster than it should be and I could see some of his muscles quivering. He was also very drawn up in his flank. I started to think maybe he has heat exhaustion.

I immediately got him out and began to spray his legs and chest to get his temperature down. I called the vet while I was spraying him and we went over his symptoms. My vet was also sure it was heat exhaustion, and recommended giving him 10 cc’s of banamine and continuing to spray him off for 30 minutes to get his temperature down. He also recommended not feeding him for the night and to give him plenty of water and keep him in a cool place.

After getting the banamine and spraying him for 30 minutes, he seemed to be much better. He was cooler and his temperature and respiration were back to normal. Then I set up some fans in a stall and moved him to the barn and gave him plenty of water. I monitored him throughout the night, and he stood behind the fans all night.

This was a good reminder that even after a ride and cooling a horse out that they can still actually be over heated or have heat exhaustion. My horse had seemed completely cooled out and seemed fine when I put him up. Luckily, I noticed him and his symptoms right away when I went back outside to check the horses.

Signs of Heat Exhaustion:

  • Sweating
  • Increased temperature
  • Increased respiration
  • Increased heart rate
  • Dropping down to roll or throwing themselves on the ground
  • Drawn up in the flank
  • Muscles quivering
  • Muscles tying up

If you aren’t familiar with what “normal” respiration and heart rates are for horses, check out our blog post on this topic. And if you suspect heat exhaustion in your horse, please call your vet immediately!


14 Replies to “Heat Exhaustion in Horses”

  1. Why can’t people just leave their horses alone (in a safe place) in extreme heat? Why is the obsession to ride so important?

    1. Hi Susan, During heat waves like the one happening across the US this week, people need to watch for this for all horses, whether they are being ridden or not. In this particular story, it was only about 90 degrees outside – a perfectly “normal” temperature for Texas for a large portion of the year! That’s why we wanted to share the story – to make people aware of the signs, so they can watch for it in their own herd whenever the temperature rises. Thanks!

    2. Susan: We actually had a horse suffer from heat exhaustion last weekend. He had not been ridden at all and was in his pasture, with an enclosed, cool stall and plenty of water. Sometimes, it just happens. Our vet also had us hose him down to lower his body temperature.

  2. If you own horses, whether you ride or not, its YOUR responsibility to take care of your horses. WE choose THEM, they don’t choose us! Thank you for the information, hopefully some ppl will pay more attention to their horses…

  3. Something to really watch is the combination of heat & humidity. horses like us rely on the evaporation of sweat to cool but have a much smaller surface area to volume ratio than we do so build heat more intensely. High humidity even with temps in 70s can cause problems. A good guide line is adding the heat + humidity numbers. At 150 pay attention and limit strenuous work especially in older horses. At 160 No hard work. Between 170 & 180 horses are incapable of cooling themselves. Hosing only cools if it evaporates after and whilst the water is heating as it runs over the horse. if they are wet after you can end up with a hot wet layer that the horse still heats. use liniment in washes as the alcohol will evaporate even in high humidity. Also be very careful trailering- avoid the heat of the day and watch out if stuck in traffic any length of time. Take water.

  4. Susan,
    This just happened to one of my very well taken care of horses. She was in her barn under fans with plenty of water., as always. She hadn’t been ridden. Vet was called out, extreme temp changes caused this problem with her. I live in Texas temps had been in the upper 90’s then went to 105 suddenly. Our vet said she had been out on many calls. Thank goodness I knew what to do until the vet got here. Just because a horse is being worked doesn’t mean this will happen. Most trainer who have horses in their barns take care.

  5. To answer your questions as to why people don’t “leave their horses alone” when it’s hot. You probably haven’t considered the possibility that they simply can’t.

    I start between 12 and thirty horses per year. I focus on turning out a quality product. If I take summer off here, I decreased my potential earnin income by 25%.

    The other possibility is that you learn how to appropriately work your stock. Which I strongly recommend to every horse owner.

    An indicator that I look for is attitude. If my colts come running to the gate when I call them up to be worked, then they must not have had too many bad experiences.

    It’s not rocket science, just do your best to educate yourself properly and scientifically and LISTEN when the horse is trying to tell you something.

  6. Thanks for writing this. People forget that doing the same activities you have always done in the same weather you have always shared may not have the same outcome. Keep an eye! (Ethologists say that horses did actually choose us).

  7. The tone of these comments just reminds me once again that horse owners generally fall into one of two categories: People who keep horses professionally/for a living; and people who keep horses as pets. In either case, this is valuable information, principally because it lists the exact symptoms we should be looking for. In my case, I realize that my broodmare is operating under another entire set of stressors and I need to be extra aware of that.

  8. I live in Florida that being shared our tempatures can change from moderate with a nice breeze to blisterng hot with high humidity. I find the best thing to do for my horses, working or not, whip out the hose and allow them to come at liberty to cool down at least twice daily. I may get soaked too but enjoy cooling off as well. My barn is equipt with fans day and night. Loose minerals offered daily will also increase drinking & sweating. Keep in mind I have sporthorses so exercise is important. After workouts a cool rinse removing sweat followed by a bucket & sponge of linament & water make them happy.

  9. Thanks for the information. You gave some very helpful pointers. Electrolytes weren’t mention though and I am wondering why the vet did not recommend them? I would have thought electrolytes would have been very restorative to a heat stressed horse.

    1. Hello, Thanks for the great question. In the case of a horse already suffering from heat exhaustion or heat stroke, it is best to give electrolytes intravenously, which would need to be done by a veterinarian. Intravenous fluid therapy would be best to treat dehydration, electrolyte loss, and shock. It is important that electrolytes are used properly or they can do more damage than good, as not using them properly with water can actually dehydrate the horse further. Administering large single doses of electrolytes in the form of an oral paste, for example, can cause the gut to absorb water from the surrounding blood vessels to dilute the concentration within the gut. Short term this will worsen the dehydration within the muscle cells.
      Hope this is helpful! Thanks ~ Gina T.

  10. When working performance horses, folks often times don’t think about the water they are given them to drink. Just as much consideration should be taken as to the quality of the water they are drinking as the feed you are giving them. I’d like to offer some information that coincides with heat exhaustion and that is dehydration. If a horse is dehydrated from work or environmental conditions, it is more likely to suffer from heat exhaustion and reduction in performance. Here is a link to an article about the co-relationship between water quality, dehydration, performance and heat exhaustion – http://bit.ly/1cl0hnm

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