It’s a scorcher out there- avoiding heat stress in horses

Written by: Jenna Tranter

Published on: 06/29/2022

We all know that humans can experience heat stress, exhaustion and stroke but what about our horses? Do you know the signs and symptoms of heat stress in horses and what to do if they are in trouble?

Lets start with the basics... We all love summer but when those hot and humid temperatures soar into the 90’s-100’s our horses are at risk, especially if exercising in those temperatures. Hot weather dangers should not be ignored by horse owners- heat stress can lead to heat stroke and a whole host of problems that come with it.

What are the symptoms?

There are quite a few symptoms of heat stress and exhaustion and some of them may come as a surprise to you. We’ve listed some of those symptoms below for you:

  • Profuse sweating OR less sweat than you expect.
  • Lack of urination
  • Sunken eyes & sticky or tacky mucous membranes
  • High body temperature of 102 degrees and up- remember that horses should have a regular temperature of 98-101F
  • Rapid heart rate and pulse that continues after exercise or movement has stopped.
  • Rapid or shallow breathing- again, remember that the average horse takes 8-18 breaths per minute
  • Skin pinch/tenting test- if you pinch the skin together and the skin does not go back or loses elasticity this is a sign of dehydration
  • Muscle weakness and stumbling
  • Hot or Cold skin- skin will feel hot to the touch unless heat stress has progressed. When heat stress progresses to exhaustion/stroke the skin may feel cold as circulation slows down
  • Lethargic or slow & abnormal behaviors

Heat stroke is very dangerous- a horse experiencing heat stroke will have rapid shallow breathing, hot dry skin, and a body temperature over 106 degrees. When a horse experiences untreated heat stroke they may collapse, go into convulsions and die.

What do you do if you suspect heat exhaustion/stress?

Now that you know what the signs are, we need to know what to do if you suspect that your horse is experiencing heat stress/exhaustion. These situations should be treated as an emergency and swift action is important to avoid progressing to heat stroke. First and most importantly call your veterinarian. Once you have contacted your vet, place the horse in a shaded area. If there is no breeze, or air flow/movement try to get a fan set up for them if possible. The interior of many barns provide shade however with limited airflow they can become very hot, very quickly once the horses are inside. Thoroughly wet the horse starting at their feet and moving up their body including their head. Hosing their chest and between the hind legs may provide them with additional relief. Cold water should be avoided- cool water is best when possible. Offer your horse small amounts of water every 15 minutes while you wait for your veterinarian to arrive.

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Are some horses at a higher risk than others?

Much like with humans there are definitely horses that are at a higher risk of heat exhaustion/stress and stroke than others. Elderly or geriatric horses are at a higher risk as well as horses that are overweight or are in poor body condition. Horses that are in direct sunlight when temperatures climb over 100F with humidity are also at a higher risk. As mentioned earlier, sometimes barns can be very hot with little airflow. Horses that find themselves in poorly ventilated stalls or confined to trailers are also at higher risk. Horses that do not drink enough or are not provided with access to salt or electrolytes fall into the higher risk category. Finally, horses that have moved from cooler climates to warmer climates without time to adjust are also at risk.

What can I do to reduce the risk of heat stress/exhaustion?

There is a simple mathematical formula that will tell you whether or not it's too hot to be riding, trailering or competing with your horse. To calculate the heat index you need to take the temperature in Fahrenheit and add the percentage humidity together. If the sum is below 120 there is very low risk in exercising your horse. Heat indexes between 130- 150 are also okay to exercise your horse in however you should anticipate sweating and ensure your horse has access to water afterwards to rehydrate. It is also important to cool your horse before offering water. When the heat index rises about 180 your horse should not be exercised or ridden. Beyond using the heat index we have included some tips for you below:

  • Ensure your horse is being given electrolytes during ‘heat waves’ to ensure their electrolytes are being replenished. I personally give my horses electrolytes throughout the summer regardless of if they are being ridden
  • Salt, salt and more salt- even if your feeding electrolytes giving you horse free access to salt is vital during periods of heat.
  • Water, water and more water! If supplying electrolytes and salt you need to ensure they have free access to clean water. Salt and electrolytes will encourage drinking. Cool water is preferred as it helps the stomach empty faster.
  • Ensure your horse is properly cooled out after rides, especially before offering water.

Finally, and most importantly, use common sense! If it’s too hot for you to want to exercise it’s probably not worth the risk to you or your horse. If you're not sure, the heat index formula is your best bet to gauge whether or not it's okay to tack up.

Happy trails and stay hydrated!

Meet Jenna Tranter

Jenna Tranter is Smart Earth Camelina Corp's equine nutritionist. She is the owner and operator of Four Corners Equestrian and has been involved in the industry for over 20 years.

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About the Author

Jenna is a lifelong equestrian and lover of all animals big and small. She has both studied and worked within the industry for 20+ years in both the feed sector as well as being a coach and hunter/jumper facility owner with time spent in the UK and Canada. She holds a number of equine certifications from universities in both countries. She also has completed numerous courses in equine body work, including equi-bow, but is not a practitioner at this time due to there just not being enough time in the day! Jenna lives on her farm in Ontario, Canada with her husband, 19 horses, 2 goats, a flock of ducks, a flock of chickens, her barn cats and her 3 loyal dogs, Bosco, Evaa & Eeyore.