August Monthly Newsletter
HEAT STROKE IN DOGS
With the dog days of summer approaching, it is important to realize that overheating in the summer temperatures happens just as frequently to dogs as it does with people.
The end of July and early August provide the hottest and driest weather in Utah, and this is the time we most often see heat stroke cases.
Heat stroke occurs when ambient conditions or pre-existing health conditions prevent your pet from being able to dissipate heat appropriately. Overheating can occur in hot, humid, unshaded or confined conditions. For example, the temperature in a closed vehicle exposed to direct sun on a 75°F day can reach 120°F in 20 minutes. Overheating can occur more readily in overweight dogs, large breeds, breeds with narrow, crowded airways (e.g., pugs, bulldogs), epileptics that have had a seizure, or dogs with airway disease (e.g. laryngeal paralysis, congestive heart failure). One way the body can dissipate heat is through evaporation of fluids (panting, salivating, and sweating). Another way is to release it through vasodilation – blood vessels at the surface of the body open up to conduct or radiate heat from the skin to surrounding surfaces or air. If these mechanisms fail to release enough heat the core body temperature rises and the heart begins racing but cannot provide adequate blood pressure, resulting in heat stroke.
Normal body temperature for a dog can range from 100.5°F to 103.5°F, depending on activity and excitement. Tissues start denaturing (“cooking”) at 107°F. When this happens, the brain swells, the kidneys shut down, bacteria in the intestines translocate into the blood stream, and blood can either form clots or fail to coagulate. Any of these actions are potentially fatal, but if the body temperature reaches 110°F, even for a few minutes the dog will most likely die.
If you think your dog is suffering from overheating or heat stroke, the single most important thing you can do for it is a controlled cool down. First seek shade or a cool area away from direct sun, in air conditioning if possible. Secondly, wet the entire dog with cool water. Do NOT use ice water or ice. This will constrict cutaneous blood vessels making it harder for heat to be released and possibly cause shivering which will increase the body temperature. If available, apply rubbing alcohol to the foot pads and fan the dog. These first aid procedures should have the highest priority, even before transportation to a veterinary facility. We are going to do the same thing when your dog arrives. If you have a thermometer, take a rectal temperature and write it down.
In the hospital we will continue cooling procedures until the rectal temperature reaches 103°F, and then we stop because the temperature will usually continue to drop and it is not uncommon for the patient to become hypothermic. Because the complications are not always immediate, we will most likely do lab work, including coagulation times. Preemptive therapy such as antibiotics, antacids and plasma transfusions may be necessary. Prolonged hospitalization may be necessary if there are neurological complications such as seizures or coma.
Although heat stroke is potentially deadly, early intervention saves most of these victims. Taking precautions such as minimizing strenuous mid-day outdoor activity, carrying water for your dog, not enclosing the dog in a warm area without air circulation, and not letting your dog become overweight decrease the likelihood of heat stroke happening. Dogs don’t always have the sense to stop exerting themselves because of excitement or loyalty, so it is up to you to exercise caution and be vigilant for heat stroke. A dog suspected of heat stroke should ALWAYS be taken to a veterinarian, even if you have adequately controlled your dog’s temperature.
References:
Ettinger, et. al. Textbook of Veterinary Internal Medicine, 5thed. Saunders. 2000.
McMichael, M. Handbook of Veterinary Emergency Protocols: Dog and Cat. Teton NewMedia. 2008.
Shell, L. “Heat Stroke.”Canine Associate Database.Veterinary Information Network. 2007.
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