38 Heatstroke

Theory Refresher

A spectrum of severity is seen in dogs suffering from heat-induced illness in terms of both pathophysiological derangements and clinical consequences. It may therefore be more accurate to employ a gradation of severity from heat stress to heat exhaustion to heatstroke. Nevertheless, the general term ‘heatstroke’ will be used here.

Heatstroke results from severe hyperthermia, although a specific threshold above which heatstroke occurs has not been defined in dogs. Cellular injury may occur above 41°C and permanent brain damage is reportedly possible. Enzyme dysfunction, protein denaturation and severe organ damage may occur above 43°C and are associated with a significant increase in mortality. Further information regarding the prognosis in dogs with heatstroke is provided in Box 38.1.


Heatstroke occurs when heat gain markedly exceeds heat loss and this is predominantly due to the cooling mechanisms stimulated by the hypothalamus becoming overwhelmed. These mechanisms include:

Heatstroke may occur more readily in dogs suffering from a lack of acclimatization to warmer weather. The acute phase response and heat shock proteins may also be involved in the pathogenesis of heatstroke.

Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Heatstroke

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