Heat Stroke in Dogs

Summer is a wonderful time of year, one often filled with fun, outdoor activities. Getting together with friends and family is a priority, and getting more exercise is on most of our agendas. Especially post pandemic, people will find themselves out and on the move even more this summer, and many of these outdoor activities are made complete by bringing your dog along. Although this is a wonderful idea, precautions must be taken to keep them safe. Our companion May 2021 blog offers tips to keep your pet safe this summer, and this blog will focus on heat-related stresses, how a dog’s body temperature gets too high, and why a high body temperature can be so detrimental to a pet’s health.

How Heat Stroke in Dogs Occurs

Heat stroke occurs in dogs when their body temperature increases to 104 ℉ or higher due to increases in the ambient temperature, as opposed to resulting from a fever. Heat stroke may rapidly become life threatening, if untreated, when body temperature reaches 107 -109 ℉ or above. Body temperatures this high in dogs can lead to multiorgan failure and even death. If you worry your pet is exhibiting signs of heat stroke, immediate action is necessary.

How Dogs Cool Themselves

Dogs cool themselves through the processes of evaporation, conduction, convection, and radiation. Evaporation occurs through the process of panting. Heat is dispelled from the surface of the tongue through evaporation of water droplets on the tongue’s surface. This process is effective to a point. That said, brachycephalic dogs (those with short noses) struggle to cool themselves effectively using this method. Ambient temperatures above 89 ℉ or humid conditions also render this method less effective. Conduction relies on the transfer of heat from a warm surface (the dog) to a cooler surface. A prime example of this is a dog lying on his abdomen (less hair) on cool, shaded grasses. Convection is the cooling effect moving air provides us such as summer breezes or fans. Radiation is the transfer of heat to the environment. Radiation is not effective as the dog’s body temperature nears ambient temperature.

What actions will predispose a dog to develop heat stroke?

Heat stroke usually occurs by one of two mechanisms, 1) a dog that is not acclimated to hot temperatures begins to exercise in warm ambient conditions and overheats or 2) a dog is placed in an environment of exceedingly high ambient temperature such as an enclosed car. To some extent, the first condition may be prevented by acclimating a dog to the environment slowly. This may take up to 60-90 days but many dogs can, and do, function in very hostile environments as working dogs. Military dogs that have been properly acclimated to desert heat can function as service dogs in temperatures as high as 140 ℉. Some breeds, however, will never acclimate well to high ambient temperatures. In particular, brachycephalic dogs, such as Bulldogs and Pugs, will never become capable of cooling themselves effectively enough to allow them to jog, fetch, or play in the summer heat. As a result, walking and playing with these dogs should be done in the cool morning hours or at twilight.

Preventing heat stroke by managing a pet’s ambient temperature and environment is 100% under our control. A dog should never be left in a car in the summer. Even a car with partially open windows will heat up very quickly. The National Weather Service has performed temperature measurements in parked cars during the summer heat. The internal temperature of a parked car will soar within 1-2 hrs to temperatures well over 110-120 ℉. The temperature of seats and dashboards soar even higher, nearing 160 ℉. Even as little as 10 minutes in a parked car has resulted in the deaths of both children and pets. Just remember, pets are best left at home on hot days.

What does excess body temperature do to a pet?

Increased body temperature causes heat stroke as a result of the release of inflammatory proteins. These proteins wreak havoc on the central nervous system, cardiovascular system, kidneys, lungs, gastrointestinal system, and coagulation pathways. Body temperatures higher than 107 ℉ result in multiorgan failure as cell death occurs in response to enzyme, cytokine, and inflammatory mediator release.

Signs of Heat Stroke in Dogs

A pet with heat stroke will often have bright red gums, feel warm to the touch, pant frantically, and seem distressed. Signs progress to ataxia (walking as if drunk) and possible seizures. Severely affected animals may collapse, and experience full blown shock. Signs of compromised coagulation pathways will result in red dots (petechiae) on exposed skin. Bloody urine, bloody stools, or vomit may also occur.

What to do if your pet is showing signs of heat stroke?

If your pet is showing signs of heat stroke, call your veterinarian immediately. As soon as possible, cool the skin with cool or tepid water (NOT ice water, as this can cause your pet to go into shock), move your pet into the shade, and get them into an area with a cooler ambient temperature, or where fans are present to move air over them. Transport to the veterinarian in an air conditioned car, if possible, you can cover your pet with towels soaked in cold water for the trip. Depending upon the severity of the heat stroke, how high their temperature peaked and for how long, your pet may require extensive intervention for cardiovascular support. Dogs that experience shock or multiorgan failure will not survive. Rest assured that prevention is easier and more effective than a cure.

Remember the following tips to prevent heat stress in your pet:

Never keep your pet in a hot car, even if parked in the shade with windows cracked.
Acclimate your pet slowly to outdoor play in the summer.
Play during the cooler periods of the day– morning and evening.
Remember that short nosed breeds, obese dogs, elderly dogs, and dogs with laryngeal and cardiac diseases are more prone to heat stress.
Never hesitate to call Longwood Veterinary Center if you have any questions or concerns about your pet’s health and well being.