Exercising, even moderately, in mid-day summer heat, you are at risk for dehydration and, possibly, heat stroke. But your horse is 3 to 10 times more likely to succumb to heat stress than you are. Michael Lindinger, an animal and exercise physiologist at the University of Guelph in Ontario, Canada, recently gave a workshop focused on his research into the response of horses to heat, and had some valuable tips for keeping your horse healthy in summer.
Things you should know about horses and heat...
1. "It only takes 17 minutes of moderate intensity exercise in hot, humid weather to raise a horse's temperature to dangerous levels."
2. If a horse's body temperature shoots up from 98.6° to about 105.8°F, the temperature in his muscles may be as high as 109.4°F. The proteins in his muscles start to "cook" at this temperature, and he may suffer hypotension, colic, and renal failure.
3. Horses rely on sweating to cool them off through evaporation, but only 25 to 30 percent of the sweat produced is effective in cooling the horse, though in humans up to 50 percent of sweat produced has a cooling effect. A horse can sweat up to 30 litres per hour in hot, humid conditions, and what doesn't evaporate just drips off his body.
4. It's not just water your horse is losing; it's electrolytes. They are lost in the "salts" of horse sweat that are 4 times more concentrated than in humans.
5. Giving your horse plain water dilutes their body fluids, which causes them to sweat more, losing more water and electrolytes. (This happens to humans during heat stroke, as well.)
Tips for protecting your horse from overheating...
1. Replacing the electrolytes is a primary concern. This should be done over time by teaching your horse to drink water with electrolytes. "Start with a small amount in the water, allowing the horse to get used to the taste, and gradually increase it over days and weeks until you have reached the manufacturer's [or vet's] recommendation." There are so many electrolyte products on the market constituted differently from each other, that you really need to get your horse's veterinarian to recommend the best one for your horse.
2. Bring your horse to a cool, shady spot after exercising him, because he will also be cooled by breathing cooler air. But the cooler air must be at least 5° below that of the air he was exposed to.
3. It is very important, according to Lindinger, not to cover your horse with anything when he is sweating - no blankets or 'coolers.' The best way to keep him cool is to wash him down with cold water, scrape the water off quickly so it does not get absorbed by the hair, and repeat the process again and again until he has cooled down.
4. If you compete with your horse, make sure that you train him in the heat, rather than in the evening or morning hours when it's cooler. He will benefit from heat acclimation, as long as you provide him with the cooling solutions above.
Happy trails to you...