A dog’s primary means of heat dissipation is through panting and, to a minor degree, by sweating through the pads of her feet, explains Ted Cohn, DVM, of University Hills Animal Hospital in Denver. Panting allows the dog to move large volumes of heated air away from her body core to the outside. Additionally, that same air moving over a highly vascular [having many blood vessels], wet tongue produces an evaporative effect. That helps to cool the blood and regulate the dog’s body temperature.
But soaring heat and humidity hinder that effort. High humidity means that water can’t evaporate very well, says Ruth E. Chodrow, VMD, of At-Home Pet Care, a pet house-call service in Fishersville, Va. High temperatures mean the dog has to pant faster and faster to evaporate the water, and if the temperature gets too high, the dog simply can’t cope. Heat stress and heatstroke follow.
When a dog overheats, her body temperature can shoot up rapidly from the normal 101 or 102 degrees to 105 degrees and beyond, Chodrow says. Above 105 degrees, the dog cannot get sufficient oxygen to its tissues, and brain damage can occur. Above 108 degrees, the cells of the kidneys, liver, and GI tract sustain severe damage, and the cells can die.
Recognize Heatstroke’s Signs
Heatstroke’s early signs include rapid breathing, rapid heart rate, thick drooling saliva, and a dry nose and mouth. The dog often has a panicked or wild expression, Chodrow says. If you lift up a lip, the gums above the teeth will be a muddy grayish-pink or a brick-red instead of their normal clear pink color. As heatstroke progresses, the dog may stagger or have seizures. In advanced stages, she may show bloody diarrhea, coma, and death. Heatstroke is a medical emergency: If untreated, it can be fatal.