IIntroduction

Heat stroke is a heat-illness caused by exposure to extreme, non-pyrogenic environmental temperatures which results in elevation in body temperature and direct hyperthermal injury to body tissues. Its complex pathophysiologic state is precipitated by alterations in normal cooling functions resulting in improper thermoregulation. Several pathologic diseases exist in dogs that perpetuate these hyperthermic events. The purpose of this article is to briefly inform veterinarians about the components of normal thermoregulation, pathophysiologic mechanisms of extreme heat exposure, and clinical signs of heat stroke in dogs, clinicopathologic findings, and recommended treatment for heat stroke.

Although heat stroke could potentially strike cats as well as dogs, for unknown reasons it has been reported only in dogs. It may be due to the fact that cats are kept indoor more often than dogs. Also, there size usually allows them to crawl in tight places or under objects where most dogs are prevented access. In fact, I could not find one report of heat stroke in a cat. This was an odd finding, as cats are common pets that are transported in vehicles also. Vehicle-entrapped heat stroke is a common problem reported in humans and in veterinary medicine. However, caution must be exercised when extrapolating results from human hyperthermia studies to hyperthermia in dogs. Several animal models have been established by investigators in heat related studies, and dogs were not identified as suitable candidates due their non-similarity to man in response to high temperature. Nevertheless, a brief review of thermoregulation will aid in the understanding of heat stroke and its proper treatment in animals.