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by Maren Bell Jones DVM, MA
The dog days of summer are here and it is more important than ever to keep your dog safe in these hot months. Heat injury is the term used to describe heatstroke or heat exhaustion in dogs. The average body temperature for most dogs is around 99 to 102.5 degrees F. As mammals, our temperatures usually stay within just a few degrees of this, especially while at rest. However, very warm temperatures can quickly spike a dog's body temperature and lead to dangerous and even deadly heat injury.
Unlike humans, dogs have very few sweat glands (mostly on the bottom of their feet) and they instead cool themselves by panting. Brachycephalic dogs that have a flattened muzzle and skull, such as bulldogs, Boston terriers, pugs, lhasa apsos and boxers, are more prone to overheating because they don't cool themselves as efficiently by panting as dogs like Labradors or German shepherds with longer muzzles. Brachycephalic breeds are often not allowed to fly in the cargo portion of airplanes during the hot summer months due to these risks. While owning a dog with a shorter muzzle is no excuse not to get exercise and enjoy the summer, avoid taking the more extreme brachycephalic breeds like English bulldogs out much past 80 F. Taking walks early in the morning or after the sun has gone down is a good way to beat the heat for both people and the dog.
Body condition is another variable. Lean dogs tend to do better in the heat than dogs carrying extra weight. A lean military working dog in Afghanistan or Iraq may be able to tolerate outside temperatures of over 110 F when doing their job, while an overweight pug might really struggle with temperatures over 75 F. Always ask your veterinarian about what your dog's ideal body condition and weight should be.
Acclimation to hot weather should be done slowly. If you are planning on a backpacking trip with your dog in the summer, bring him outside with you in the spring months on shorter hikes locally. Even just having them outside with you while you do yard work under supervision can help them get used to temperatures above your air-conditioned house. Also, keep your dog well-groomed. I do not recommend shaving dogs in the summer, especially to their skin, but keeping the undercoat brushed out will help a lot. In addition, never leave your dog in a car unattended in warmer months.
Whether your dog is a seasoned canine athlete or a weekend warrior playing ball in the backyard, warm-ups and cool downs are very important. A potentially fatal condition called gastric dilatation and volvulus (GDV or "bloat") is a serious emergency and results from the stomach rotating on itself and cutting off the blood supply to the stomach. To prevent GDV, in addition to not feeding your dog for two hours before or after a workout, watch their water consumption carefully and cool your dog down right after strenuous activity. For example, after a session playing water retrieve games, avoid the temptation to place a large bowl of water in front of your dog and stick them back in their crate. You can give your dog five to 10 laps of water, but after that, walk them on leash at a comfortable pace for at least five minutes to cool down before offering more water. This prevents them from panting so heavily while drinking the water. We do not want to restrict the amount of water they get, but just let them cool down slightly first.
While your dog is enjoying the outdoors with you, notice what your dog's tongue looks like. A dog panting mildly will have a relatively flat tongue, whereas a dog who is panting heavily will have a tongue shaped more like a scoop at the end with the edges curled over. Once you notice the scoop shape in the tongue, slow down your activities and cool your dog off.
In addition to monitoring your dog's tongue, learning how to take your dog's rectal temperature is an important skill to know for first aid, especially if you suspect your dog might be suffering from heat injury. Keeping the experience positive will make it easier on your dog and your veterinarian during wellness checkups as well as in an emergency.
A dog's body temperature may increase into the 102 or 103 F range when exercising in warm weather and this is normal as long as they are not showing signs of distress. Dogs in the 104-105 F range should stop what they are doing and be cooled immediately. Dogs above this range, especially if they are showing signs of heat injury (lethargy or seeming mentally "out of it," harsh breathing sounds, thick ropey saliva, collapse, pale or very dark mucous membranes), should immediately receive emergency medical treatment from a veterinarian.
Recommended advice for heat injury first aid is varied. Some sources advocate submerging the dog in a small pool or bathtub of ice water, while others suggest that ice water may actually constrict blood vessels near the skin and trap heat in the body, so cool or lukewarm water is best. Taking cold packs and placing them in the underarm and inner thigh area may help with cooling while you are transporting the dog to a veterinarian. Make sure to stop cooling measures once your dog has reached 103 F, as some dogs may show a condition called rebound hypothermia where the body temperature continues to dip dangerously low after too much cooling. Your veterinarian will likely wish to start IV fluids and other supportive care measures.
Owners often want to know about supplements to add to the dog’s drinking water to help them avoid dehydration. Dogs do not lose as many electrolytes as humans do, since dogs sweat very little. So far, water supplements seem to have mixed results in preventing heat injury. Being mindful of not overdoing it in hot weather, giving your dog plenty of cool, clean water, and knowing when to slow down and cool off seem to more important than supplemental electrolytes. Play it safe this summer and when in doubt, move to a cooler spot!
Note: this article appeared in the August/September 2013 issue of Pet Project Magazine