When temperatures rise, clinics may see more victims of heatstroke. Some of the most common causes of this life-threatening condition in pets include:
Being left in a hot car
Exercising outside in warm weather
Prolonged, unattended use of a dryer after bathing
Being left outside with no water or shade
Brachycephalic breeds, including bulldogs, pugs, and Boston terriers, are pre-disposed to heat stroke due to their anatomy. Older and overweight animals are more susceptible to heatstroke as well.
What Is Heatstroke?
Heatstroke, also known as severe hyperthermia, is very dangerous because it can lead to multi-organ failure due to inflammation, changes in tissue perfusion, and altered coagulation. Neurologic signs such as collapse, ataxia, and seizures can be seen due to decreased blood flow to the brain.
Renal failure is a relatively common aftereffect to heatstroke because of decreased blood flow to the kidneys. Severe hyperthermia can lead to myocardial necrosis; arrhythmias can be seen due cardiac hypoperfusion, and the pulmonary endothelium can be damaged, leading to pulmonary edema.
Blood flow can also be compromised to the gastrointestinal tract leading to hemorrhagic gastrointestinal signs, bacterial translocation and sepsis. Disseminated intravascular coagulation (DIC) can occur as well.
How to Treat a Dog or Cat with Heatstroke
If a patient presents to you with significant hyperthermia, stabilize the patient first and then get a history. Typically, IV fluids and thermoregulation are very important. Fans, cool towels, an icepack on the fluid line, and water on the paw pads can be helpful to get the temperature under control.
Often these patients are in shock and need fluid resuscitation. Because pulmonary edema can be seen with heat stroke, patients may need oxygen support as well. Once you stabilize the patient, blood work and other supportive measures can be performed. Symptomatic and supportive care may include gastroprotection, antibiotics, mannitol, and dextrose.
When taking a history from the owners, ask about any situations mentioned above where the patient could have been at risk for heatstroke. Because prolonged seizures can also lead to hyperthermia, it is important to ask if the patient’s signs started with seizing.
There are a few products that can lead to hyperthermia as a result of a toxicity so asking about any possible exposures can be helpful as well. Products that can lead to severe hyperthermia include hops (humulus lupulus), 5-htp, marijuana, methylxanthines, such as caffeine and chocolate, and any product that can cause serotonin syndrome.
The prognosis for patients with heatstroke tends to be guarded. If the patient presents hypoglycemic, has prolonged clotting times, develops renal failure, or develops DIC, then the prognosis is poor.