Heat, humidity and horses don't mix well

It only takes 17 minutes of moderate intensity exercise in hot, humid weather to raise a horse’s temperature to dangerous levels, according to a recent study by Professor Michael Lindinger.

Temperature extremes are never good for riding horses. It wasn’t that long ago we were battling near record-breaking cold temperatures. Now, the heat and humidity of summer has arrived.

Heat, humidity and horses don’t mix well. The horse’s physical body is not as efficient with heat. They can deal with colder temperatures much easier. Humans can actually handle higher temperatures of heat and humidly than horses. The difficulty lies in the horse’s basic muscle structure.

“It only takes 17 minutes of moderate intensity exercise in hot, humid weather to raise a horse’s temperature to dangerous levels,” according to a recent study by Professor Michael Lindinger. “That’s three to 10 times faster than in humans.”

Horses feel the heat much worse than we do and the effects can be serious, explains Lindinger, an animal and exercise physiology at the University of Guelph, Canada. If a horse’s body temperature shoots up from the normal 100 degrees Fahrenheit to 105 degrees Fahrenheit due to the heat, the temperatures within their working muscles may be as high as 110 degrees Fahrenheit.

“At that temperature, the proteins in their muscles begin to break down and for lack of a better word, cook. Horses suffering excessive heat stress may experience hypotension, colic and renal failure,” Lindinger said.

Due to the horse’s muscle size, which is larger than a human, they have a higher percentage of active muscle than people do during exercise.

When muscles are being used, they produce a lot of heat. Horses rely on sweating to cool them off and they can sweat 4-6 gallons in cool, dry conditions and up to almost 8 gallons per hour in hot, humid conditions. Unfortunately, only 25-30 percent of the sweat produced is effective in cooling the horse off by evaporation.

“Because so much more sweat is produced than can be evaporated, the rest just drips off the horse’s body,” Lindinger said. “By comparison, up to 50 percent of the sweat people produce is evaporated from our bodies during exercise and helps to cool us.”

The other issue we see with horses and sweating is that the salts in horse sweat are four times as concentrated as in human sweat. This means that the salts the horses expel have to be replaced. By just giving the horse water it will not rehydrate a dehydrated horse.

When a horse drinks plain water it actually dilutes their body fluids, and their bodies respond by trying to get rid of more water and more electrolytes. A very dangerous situation is beginning.

To break this dangerous cycle give your horse an electrolyte solution, water with the right proportion of salts dissolved in it to replace sweat losses during warm and hot weather. Use a commercial electrolyte solution to add to your horse’s water. Start small and gradually get them use to the taste. Another option, which allows you to better monitor their intake of electrolytes, is the oral paste electrolyte mix you can find at veterinary and tack shops. Give it to your horse after a workout.

To cool a horse off look for shade and breezes. Never use a blanket or cooler on a horse that is sweating. The best way to cool a horse quickly is to rinse the horse’s body repeatedly with cold water and to scrape off the excess water.

“You can cool a horse two degrees in ten minutes this way: pour on the water, scrape it off, pour on more, and just keep repeating it,” Lindinger said. “The scraping part is important because otherwise the water will be trapped in the horse’s hair and will quickly warm up. By scraping and pouring on fresh, cold water you keep the cooling process going.”

The basic “Too Hot to Ride” rule is take the temperature number and add it to the humidity number of the day. For example, if its 80 degrees Fahrenheit and the humidity is 50 percent, that equals 130.

If the total number is 130 or less, you are safe to ride. Between 130-170, take caution. The horse is going to have difficulty in cooling off. If the total is 170 or above, DON’T RIDE. It’s too dangerous.

Have a safe and happy summer. Happy Trails!

LORI RICIGLIANO is a horse judge, trainer, riding instructor, equine photographer and clinician. She also hosts a weekly syndicated equine radio talk show “Hoof Beats with Lori”. Lori has held her horse judges license as a USEF / AHA — “R” rated licensed horse judge for more than 25 years and currently operates Ricigliano Farms Horse Training and Riding Academy near Kent, Minn. She can be reached by email or phone for any questions at 218- 557-8762 or riciglianofarms@gmail. com. Her website is www. RiciglianoFarms.com


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