Heat stroke can occur when canine body temperatures rise to 104-106 degrees. As dogs cannot rely on sweat glands to dissipate heat, they can be prone to heat stroke when exposed to high environmental temperatures. Any temperatures above 70 degrees combined with exercise and poor access to water can facilitate heat stroke. Exertional heat stroke occurs when internal heat generated by strenuous exercise is not adequately dissipated and body temperatures rise to dangerous levels.
Signs vary depending on the degree and duration of temperature elevation. Panting and hyperthermia are the most common signs. The animal may be dull, weak and wobbly, collapsed, convulsing or in a coma. Respiratory and heart rates are usually high. Gums of the mouth may be bright red. Pulses may be weak. Vomiting and diarrhea may occur. Decreased urine production (kidney failure) and jaundice (liver failure), infection and widespread bleeding can also occur. Diagnosis is based on finding an extremely high body temperature, a history of exposure to heat and compatible clinical signs.
Common laboratory changes caused by heat stroke include dehydration, prolonged blood clotting, abnormal kidney and liver tests and electrolyte abnormalities.
Heat prostration is an emergency! The goals of therapy are to lower body temperature, treat shock and other organ damage and prevent infection. As soon as you realize your pet has heat frustration, remove it from the source of heat and wrap the animal in a cool wet towel for immediate transport to a veterinary hospital. Treatment for shock involves the administration of intravenous fluids and supplemental electrolytes. Other therapies, including seizure prevention and mechanical ventilation, may be needed.
Most animals with heat stroke require intensive monitoring throughout the initial therapy and for a few days after the emergency has resolved. Prognosis depends on the severity and duration of hyperthermia and the presence of secondary organ failure. Animals surviving heat stroke are prone to a recurrence, so preventive measures are important.
Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.