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July 1, 2014
by Dr. Timothy B. Hackett
On a typical summer day, temperatures easily top 90 degrees F in much of the country, and it likely feels much hotter for many dogs. In fact, heat-related illness is one of the most common preventable causes of multiple-organ failure in dogs.
Consider a few basics about canine physiology: Unlike humans, dogs don’t sweat to regulate body temperature; panting is the main mechanism for evaporative cooling of the body. A dog’s long nose also helps to cool air and regulate temperature.
But heat easily overpowers these functions, especially if a dog is sick, is older and less able to effectively regulate body temperature, has a heavy coat, or is flat-faced, called brachycephalic. Moreover, dogs rarely resist a chance to hike, run, fetch and play – even if this exercise leads to overheating.
Put together, these factors mean pet owners must be attuned to the hazards of heat for their dogs and take steps to avoid heat-related illness.
Heat-related risks came into sharp focus in late June, when 20 dogs died at a boarding kennel near Phoenix after the facility’s air-conditioning reportedly malfunctioned.
Here in northern Colorado, Animal Protection & Control officers respond to about five calls every summer day from people worried about the welfare of dogs left in hot cars, according to the Larimer Humane Society. Leaving a dog in a hot car – even for a short time – is classified in the city of Fort Collins, Colo., as animal neglect and is subject to a fine of $250.
Why the concern? Temperatures spike quickly in parked cars, even in the shade and even with windows rolled down. If it’s 90 degrees F outside, the temperature inside a car will jump to about 110 degrees F in just 10 minutes and will continue to rise from there, research shows. That’s killer heat for a dog.
A dog’s normal body temperature hovers around 101 degrees F, and a dog’s core temperature may approach 110 degrees F or higher if it is left in a hot car. Serious symptoms of heat-related illness typically develop when a dog’s body temperature rises above 108 degrees F.
At that point, thermal injury to cells can literally cook proteins, inactivate enzymes, destroy cell membranes and damage the cells’ ability to generate energy. This can lead to organ failure and death.
In the past decade, 36 dogs were treated at CSU’s James L. Voss Veterinary Teaching Hospital for heat-related illness after being removed from hot cars. One-third of these dogs died from their injuries.
Yet heat-related illness much more commonly results from exercising dogs until they are overheated. This occurs in poorly acclimatized dogs and those having a harder time dissipating heat. The result often is a condition called laryngeal paralysis – and in the past 10 years, the CSU Veterinary Teaching Hospital has treated 519 cases of laryngeal paralysis.
Laryngeal paralysis occurs when the larynx, or voice box, fails to properly open for airflow, making it difficult for a dog to pant effectively. It is marked by loud wheezing when a dog breathes and is a common ailment of older dogs.
Here are factors that predispose dogs to serious heat-related illness as environmental temperatures rise:
Remember that dogs age faster than people – so your 7-year-old golden retriever might not cope with a summertime hike or run as easily as you might think, even if he acts eager to go.
Make sure to ask your veterinarian about the risks of heat-related illness, and specifically about your dog’s ability to handle heavy exercise.
Dr. Timothy Hackett is director of Colorado State University’s James L. Voss Veterinary Teaching Hospital. He is a specialist in veterinary emergency and critical care.