Citation

Hemmelgarn C, Gannon K. Compend. Contin. Educ. Vet. 2013; 35(7): e1-e6.

Copyright

(Copyright © 2013, MediMedia Animal Health)

DOI

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PMID

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Abstract

Heatstroke is a common veterinary emergency that, depending on the severity of injury, can progress to a life-threatening condition. Heatstroke can be classic (nonexertional) or exertional. Classic heatstroke develops when the body is exposed to high external temperatures, whereas exertional heatstroke is caused by strenuous exercise. Thermoregulation is the intrinsic ability of the body to maintain core body temperature within normal limits through an intricate balance of heat conservation and heat dissipation. Severe disease ensues when persistent hyperthermia causes injury to the body for which these mechanisms can no longer adequately compensate. The first stages of heatstroke are characterized by initial thermoregulation, acute phase response, and activation of heat shock proteins. The organ systems most commonly affected during heatstroke are the gastrointestinal tract and the coagulation, renal, cardiac, pulmonary, and central nervous systems. Heat-related illnesses are prevalent in human and veterinary medicine. Over a 9-year period, one study estimated that 55,000 human cases of heat-related illness were treated in emergency departments in the United States. The Hebrew University Veterinary Teaching Hospital in Rehovot, Israel, reported 40 cases of heatstroke in canine patients between 2005 and 2006. During summer months, all emergency-room cases should be evaluated closely for clinical signs of heatstroke. To limit the incidence of heat-related illnesses, exposure to heat should be minimized for high-risk populations with predisposing risk factors. Heat-related illnesses are categorized based on clinical signs and the body temperature of the patient. These illnesses range from mild to severe based on the length of heat exposure and whether the patient has any underlying predisposing factors. Heat stress is the mildest form of heat-related illness, and heatstroke is the most severe. Numerous definitions have been proposed to describe the intricate disease process of heatstroke. In humans, the classic definition is a severe illness characterized by a core temperature >104°F (>40°C) and central nervous system abnormalities; however, a more thorough definition of heatstroke in humans has been proposed: "A form of hyperthermia associated with a systemic inflammatory response leading to a syndrome of multi-organ dysfunction in which encephalopathy predominates."3 A similar syndrome has been described in veterinary patients... Exogenous and endogenous factors can predispose a patient to the development of heat-related illness. Predisposing factors can impair the ability to dissipate heat and/or cause increased heat production. Exogenous factors include lack of acclimatization, confinement to an area with limited ventilation or shade, elevated environmental humidity, water deprivation, and administration of specific medications. In veterinary patients, exposure to high external temperatures in vehicles is common. In <40 minutes, the temperature in an automobile can reach 145°F (62.7°C) during the summer months, even in a light-colored vehicle with the windows partly opened..... KW: Hyperthermia in automobiles

Language: en