Looking for a cool shady place with a cold drink to escape those warm summer temperatures? Maybe a dip in the pool or the lake will provide some relief. Some of us just hate to go outside the house during the middle of the day when we are fortunate enough to have an air-conditioner in those midsummer months. Just think of how bad it would be to have on a fur coat and have to pant to release excessive heat. Don’t forget your best 4-legged friends when trying to escape those dog days of summer. Your pets are more sensitive to heat stroke than you might think.

Our pets cannot perspire or sweat like we do to cool our bodies off. If the air is thick with moisture, under conditions of high humidity, the efficiency of panting to release heat is greatly decreased and complicates the body’s ability to cool down. Most dogs will need to find a cool place during much of the day to hide from the unrelenting sun and to provide some supplemental cooling power to panting. Many dogs will dig in the dirt in order to provide some relief and are reluctant to become at all active during the heat of the day.

Short-nosed or brachycephalic breeds of dogs, obese, and older dogs with heart or lung disease are particularly susceptible to heat stroke. The most common cause of heat stroke in the dog occurs when the dog is trapped in a closed automobile. Heat stroke in cats is often seen when they become trapped in a clothes dryer.

Hyperthermia (above normal body temperatures) occurs when the body temperature is over 102ºF. The severe hyperthermia associated with heat stroke usually occurs with body temperatures from 105ºF to 110ºF.

At temperatures above 106ºF, the parenchyma of many cells undergoes damage though the denaturization of proteins as well as chemical and enzymatic degradation. When body temperatures rise above 110ºF animals have only a few hours to live unless the temperature is brought back within a normal range. The tissues most sensitive to heat include the kidneys, liver, gastrointestinal tract, and the brain.

The more common clinical signs of heat stroke include excessive panting, congested hyperemic mucus membranes, vomiting, diarrhea (often bloody), dehydration, hypersalivation, and hypovolemic shock. The affected pet produces very little urine (oliguria), and when they urinate will pass large amounts of protein with their urine (proteinuria). Cerebral edema (swelling of the brain) may result, causing seizures, hypoventilation, coma, respiratory and cardiac arrest. Disseminated intravascular coagulation (DIC) may occur early in severe cases or be seen shortly before death occurs and is usually attributed to liver damage affecting the production of proteins and blood coagulating (clotting) factors.

Emergency treatment consists of lowering the patient’s body temperature, typically by immersing the animal in cold water. In severe cases a cool water enema may assist in reducing the core body temperature quickly but will make it harder to determine what the core body temperature is at any point in time. Box fans may be strategically placed to provide more rapid cooling of the wet pet. Cerebral edema may be prevented through the use of corticosteroids, or in advanced or severe cases by the use of mannitol. Dehydration should be corrected through the use of intravenous fluids. Compromised cells may allow for bacterial growth and septicemia (the spread of bacteria through the bloodstream) therefore antibiotics should also be given. At least one author suggests that Oxyglobin® may improve oxygen delivery to affected tissues. Pets that seizure will require anticonvulsants.

Even in recovered individuals there may be permanent central nervous system dysfunction such as seizures, and the pet may be more prone to future episodes of heat stroke.


References:

Ettinger, Stephen, and Edward Feldman. “Textbook of Veterinary Internal Medicine.” Elsevier/Saunders 6th Edition. 2005. Vol. 1. Pp 437-440.

Guyton, Author. “Textbook of Medical Physiology.” W.B. Saunders. 5th Edition. 1976 P. 967-968.

Kirk, Robert, and Stephen Bistner. “Handbook of Veterinary Procedures and Emergency Treatment.” 1981. W.B. Saunders Co. Pp. 81-82.