Preventing Problems from Heat Stress

Posted by Joyce Harman, DVM, MRCVS on Jun 1st 2022

Preventing Problems from Heat Stress

How to check heart rate and monitor sweat patterns to keep your horse safe this summer!

Riding in the summer heat can be fun and safe with a little preparation. Obviously, there are bugs to contend with, but today we will discuss heat stress and how to monitor for it. Most people pay attention to how rapidly the horse is breathing after exertion such as going up a hill or having a good gallop. But heart rate is much more accurate and important. Endurance riders know this. They have learned how to take their horses’ heart rate and do it all the time.

You do not have to be an endurance rider to benefit from taking heart rates. Every horse owner should know how to do it and should have a stethoscope handy in the barn’s first aid kit. It does not have to be a fancy, expensive stethoscope at all. A 10 dollar one will do just fine. You can count the number of beats for 15 seconds and multiply by 4.

The respiratory rate is influenced by temperature and most importantly by humidity. The higher the humidity, the higher the respiratory rate, even when the heart rate is low. Conversely, in dry climates, the respiratory rate may not be that high, but the heart rate could be.

The heart rate of a horse can go over 200 beats per minute with strong exertion such as galloping up a hill, running a race or working beyond her level of fitness. You will not see those high rates unless you have a heart monitor recording during the exercise. The most important count is the speed at which the heart rate recovers from that high point. From the end of the gallop or hill to the time you pull up, get off and find the heart to listen the rate will have dropped to somewhere around 60 to 100. Within another minute or two, it should be well below 80 beats per minute.

Unfit horses and those that are becoming heat stressed will have heart rates that stay above 80 for five to 10 minutes. Fit horses will have heart rates that drop rapidly towards 64 and below. If you check the heart rate and it's staying high, find a cool place, some water (a stream, puddle, hose) and cool the horse off. Stop riding until the heart rate recovers then slow down and make your way home.

Also watch for sweat patterns. With the extremes of heat the country is experiencing, warm nights can contribute to anhydrosis (the inability to sweat). This can be life threatening, since the horses can literally cook inside with no way to cool. If this occurs, wash them off with cool water and if they seem stressed, call your vet. There are herbal formulas that can help (and also actually beer, perhaps most especially Guinness helps non-sweaters).

Overweight horses are significantly more affected by heat since they have a larger body mass to cool. So, if your horse is heavy, exercise for sure to help with weight loss, but do so carefully. You may need to ride in the early morning or skip it entirely on extremely hot and humid days.

Overweight horses need metabolic help to assist with weight loss, along with dietary changes. Harmany Equine’s OB and INR Formulas and Hilton Herb’s Insulite will help change the metabolism in the Insulin Resistant obese or just chubby horse.

Dr. Joyce Harman graduated from Virginia Maryland Regional College of Veterinary Medicine and became a member of the Royal College of Veterinary Surgeons. She is certified in veterinary acupuncture and veterinary chiropractic. She has completed advanced training in homeopathy and herbal medicine and in Chinese medicine. Dr. Harman has served as president of the American Holistic Veterinary Medical Association, chairman of the Alternative Medicine (Therapeutic Options) Committee for the American Association of Equine Practitioners, and has been a member of the task force on alternative medicine for the American Veterinary Medical Association (AVMA).  Dr. Harman owned Harmany Equine Clinic, Ltd., a holistic veterinary practice, in Washington, Virginia for over 30 years. Visit