Heat stroke occurs when a dog or cat’s internal regulatory mechanisms cannot maintain a normal core temperature of 101 to 102 degrees Fahrenheit. When the core temperature rises above 105 degrees, all body systems begin failing rapidly. This situation is truly an emergency and requires a pet owner’s quick intervention to expedite cooling and prevent permanent organ damage or death. Heatstroke can occur in all breeds with brachycephalic (pug-nosed), and long hair breeds being especially vulnerable. Obese animals are also more prone to overheating. It is not uncommon to see heatstroke patients in the veterinary hospital during the spring before temperatures soar into the 90’s and 100’s. High humidity allows heat to transfer through the skin more easily. Leaving a pet in an unventilated automobile is a very common cause of heatstroke. The temperature inside a closed car will reach 102 degrees in 10 minutes on a beautiful 85 degree day. In 30 minutes, the car will reach 120 degrees or more inside.
An animal suffering from heatstroke may be standing listless or lying on its side unresponsive. It will be hyperventilating (very rapid panting) and have thick ropey saliva hanging from the tongue and mouth. The gum tissue and lips will however be tacky and dry. The gum color will be blood red early in heatstroke and turn grey-blue as shock sets in. Seizures occur as the brain overheats and cascades of physiological breakdowns occur. If it is possible to take a rectal temperature, it may read 106 or higher. The pet must be cooled quickly and taken to the veterinarian as soon as possible.
It would seem logical that icy cold water would be the best choice to cool the pet rapidly, but it will actually cause capillaries at the surface of the skin to close. The circulation is already compromised during heatstroke, and cooler blood will not return to the core as quickly if very cold water is used. Instead, room temperature water is more effective. Concentrate on the trunk and the head. Do not try to force an animal in heatstroke to drink water; it will only aspirate into the lungs while panting, or cause vomiting which leads to further electrolyte loss. Take a rectal temperature often, and stop cooling when the thermometer reads 103 degrees. It will continue to drop. Because the body’s regulating mechanisms are not functioning properly, it is very easy to cause hypothermia (sub normal core temperature) if cooling is continued too long. Towel the excess water from the coat and allow the pet to air-dry.
Get the pet to the vet! IV fluid therapy and steps to control shock should be started immediately. Other treatments that may be necessary will depend on the presenting clinical signs, but may include oxygen therapy to improve tissue perfusion of vital organs, antibiotics to prevent sepsis, and electrolyte replacement.
It is always better to prevent heatstroke in the first place. Always provide fresh water and shade, and moving air if possible, to an outdoor pet. Remember that working breeds and enthusiastic dogs will go until they drop. Keep this in mind if jogging with your dog or throwing the Frisbee on a warm humid day. Exercise with your pet early in the morning. Never leave an animal in an unventilated vehicle for any period of time. Partially rolling down the windows in a car will not provide enough ventilation, so it may be best to leave the pet at home during warm seasons of the year. Brachycephalic breeds and obese pets are especially vulnerable to the heat because of their inherent respiratory problems.