Julaine Hunter, DVM
Diplomate ABVP (Equine Practice)
LazyPaw Animal Hospitals
Hyperthermia is the scientific name for elevated body temperature. In dogs, elevations of rectal temperatures above 103°F are considered to be abnormal and hyperthermic. In the absence of illness, body temperatures in excess for 106°F are commonly attributable to exposure to excessive external environmental temperatures. Multiple organ failure and often death occur when the body temperatures reach 109°F.
Unlike us, dogs lack the ability to sweat efficiently, relying instead upon panting to exchange heat. Vigorous exercise during hot days or over-exertion in relatively low humidity and temperature situations can result in pets suffering heat stress or heat stroke.
Some brachycephalic breeds of dogs are at a greater risk because they have an anatomically restricted airway. Clinical signs of heat stroke can develop in these breeds even when ambient temperature and humidity are slightly elevated.
Hyperthermia is a medical emergency over-heating leads to tissue destruction, including critical organs namely the brain, the liver and the kidneys. Prognosis is dependent upon several critical factors:
The actual temperature the body reached.
The length of time hyperthermia persisted.
The individual’s health prior to experiencing heat stroke.
If the individual’s temperature was not extremely high and emergency treatment was instituted immediately, most healthy individuals fully recover. Others may suffer permanent organ injury and/or die as a result of complications from multiple organ dysfunction (MODs). Damage sustained by the brain’s thermoregulatory center predisposes heat stroke victims to repeat bouts of hyperthermia.
Treatment requires safe and controlled reduction in body temperature that can be achieved by pouring cool water over the head, stomach, underarms, ventral abdomen, and feet. During transport to a veterinary facility, cool cloths may be applied to these areas. Careful application of rubbing alcohol to the paw pads helps to increase perspiration by dilating the pores. A digital rectal thermometer should be used to monitor the animal’s temperature.
Aggressive cooling measures should be halted once the rectal temperature has fallen to 103ºF (39.4ºC). Animals so affected should be examined by a veterinarian, even if normal rectal temperatures have been re-established. Blood work to evaluate critical organ function is often recommended to determine the extent of tissue injury which may or may not be grossly evident.