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Monday, May 19, 2014

‘Tis the season for heatstroke

  As spring arrives and lends way to summer, many pet parents want to enjoy being outdoors with their pets more, primarily dogs.  This can include such activities as hiking, walking or running, dog parks, or simply allowing the pet to spend more time outside in their own backyard.  With the quickly rising temperature, however, comes a need for increased alertness to the signs of heat stress and heatstroke, and how to appropriately deal with it if it occurs.  Heatstroke occurs when a pet’s body temperature increases to 104.9 F or greater, after a pet has engaged in exercise/activity or been exposed to an increased outdoor temperature, and has an inappropriate ability to decrease the body temperature through normal cooling measures.   
            Human’s and pet’s bodies are designed to function at a constant body temperature that is regulated by a center within the hypothalamus located in the brain.  As body temperature begins to increase in pets, a signal is sent to the panting center in the brain.  Panting is the primary means of evaporative cooling in pets since they lack the ability to sweat like humans. Other methods to decrease body temperature through the dissipation of heat also exist, including convection (finding a cool place to lie down), and changes in blood circulation (dilation of the blood vessels to try to cool a larger volume of blood).
 In Florida, pet owners not only have to consider the ambient temperature outside, but also the humidity level.  As the humidity rises, this decreases the effectiveness of cooling through panting (the primary means of heat dissipation).  Predisposing factors that can increase the risk of a pet suffering heatstroke include lack of adequate shade outside, exercising the pet during the hottest hours of the day, obesity, brachycephalic breeds (i.e. Bulldog, Pug, Lhasa apso, Boston terrier, etc.), presence of a collapsing trachea or laryngeal paralysis, or previous history of heat-induced illness. 
Common clinical signs that may alert an owner to potential heatstroke include excessive panting, vomiting, collapse, ataxia (“drunken walk”), diarrhea, or seizures, and can progress to more severe signs such as bloody vomit (hematemesis), bloody diarrhea (hematochezia), bruising along the skin, nasal bleeding, muscle tremors, and listlessness/coma.  If an owner suspects a heatstroke, the pet should be moved into a cool shaded area or indoors away from sunlight.  The pet should then be sprayed with cool, but not cold or ice, water.  If the water is too cold, this can actually cause the blood vessels to constrict and decrease the effectiveness of the cooling measures, or it can result in cooling the pet too fast.  Place a fan on the pet, and the owner may also place cool wet towels in the armpits or the groin region.  As soon as these cooling measures are taken, transfer to the nearest veterinary clinic immediately for continued treatment. 
Even with aggressive supportive care and treatment, deaths from heatstroke can approach 25-50% in patients.  This is why it is essential to transport the pet to a veterinary hospital as soon as possible to try to manage the impact that the elevated body temperature will have on the organs, predominantly the liver, kidneys, heart, gastrointestinal, and central nervous systems.  Be vigilant during the summertime, and follow proper safety precautions to prevent furry family members from succumbing to the heat!