“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, D.V.M., of University Hills Animal Hospital. “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, V.M.D., of At-Home Pet Care, a pet house-call service. “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 degrees 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.”

Watch for risk factors
Too much exercise on a hot day or sitting in a parked car on a warm day, and your dog could suffer severely — or die. “In the enclosed space of a car, humidity builds up rapidly as the heat rises,” Chodrow says, “so moisture doesn’t evaporate to cool the dog. Even when it’s only 80 degrees outside, a car can heat up to 120 degrees in less than 30 minutes.” With extended play or work, a dog’s body naturally heats up; that rising body heat coupled with hot or muggy conditions taxes the dog’s ability to cool herself.

Chodrow notes that certain factors put dogs at greater risk for heat problems:

• Black coats absorb more heat than light coats do.
• Overweight dogs suffer from reduced breathing capability; extra insulation compounds the heat problem.
• Short muzzles are less effective at passing air through upper airways, so panting doesn’t work as well.
• Double coats retain more heat.Very old or very young dogs don’t regulate body temperatures as well.

How to treat heatstroke
If you suspect your dog is suffering from heatstroke, follow these steps:

• Stop the heat: First, eliminate the causes (e.g., closed car, activity), Cohn says, and then move your dog to a cooler area. Use a fan to increase evaporation.
• Cool down: Try to lower your dog’s temperature immediately, even before transporting her to the hospital, Chodrow advises. Immerse her in a tub of cool water or soak her with a garden hose. “Put an ice pack at the base of the skull to help prevent brain damage,” Chodrow says.
• Visit the vet: “Monitor the dog’s temperature with a thermometer,” Chodrow says. “When it comes down to 103 degrees, stop the cooling and take the dog at once to a veterinarian.” Heatstroke victims may sustain kidney or liver damage and might need several days of treatment and monitoring.

What you shouldn’t do is as important as what you should. “Do not soak the dog in ice water,” Chodrow warns. “Ice water will close the capillaries of the skin, preventing cooling of the internal organs. Do not use rubbing alcohol — the dog might cool down too rapidly. Do not give a heatstroke victim large amounts of water to drink as the dog could bloat; if she seems thirsty, offer her some ice cubes to lick. Do not put the dog into an enclosed crate — humidity will build up and prevent evaporation.”

Avoid the heat and add water
The best way to deal with heatstroke is to prevent it. “Never exercise your dog in the middle of a hot day; exercise or play with your dogs in the early morning or late evening to prevent overheating,” says Jeff Werber, D.V.M., of the Century Veterinary Group. “If you do go outside with your dog on a hot day, bring plenty of water and wrap a wet bandana around her neck to keep her cooler. Even better, freeze the wet bandana the night before, so it will be cooler longer.”

By planning exercise around the thermometer and carrying plenty of water, you and your dog can enjoy summertime fun — safely.