What is heat stroke?
Heat stroke is a term commonly used for hyperthermia or elevated body temperature. If a pet's body temperature exceeds 103°F (39.4°C), it is considered abnormal or hyperthermic. Body temperatures above 106°F (41°F), without previous signs of illness, are most commonly associated with exposure to excessive external or environmental heat and are often referred to as heat stroke. The critical temperature where multiple organ failure and impending death occurs is around 107°F to 109°F (41.2°C to 42.7°C).
How do I know if my pet has heat stroke?
Dogs suffering from heat stroke can have elevated breathing rates, dry or sticky gums, abnormal gum color, bruising in the gums, lethargy, disorientation, and seizures.
What causes heat stroke?
The most common cause of heat stroke or hyperthermia is leaving a dog in a car with inadequate ventilation. The dog's body temperature in this situation can elevate very rapidly, often within minutes. It is important to remember that dogs cannot control their body temperature by sweating, as humans do, because dogs have a relatively small number of sweat glands located in their footpads. Panting is their primary way of regulating body temperature.
Other common causes of heat stroke include being left in a yard without access to shade or water on a hot day, being exposed to a hair dryer for an extended time, and excessive or vigorous exercise during hot temperatures. Excited or excessively exercised dogs are sometimes at risk even if the environmental temperature and humidity does not seem high, particularly if they are kept in a poorly ventilated environment or a dog house.
Dogs with a restricted airway, such as brachycephalic breeds (flat-faced dogs such as pugs, boxers, and bulldogs), are at even greater risk. In these breeds, clinical signs of heat stroke can occur when the outside temperature and humidity are only moderately elevated. Dogs that are muzzled can also be at greater risk, since their ability to pant is restricted by the muzzle.
Any infection causing fever (pyrexia) can lead to hyperthermia. Seizures or severe muscle spasms can also elevate the body temperature due to the increase in muscular activity.
What is the treatment for heat stroke?
Hyperthermia is an immediate medical emergency. Safe, controlled reduction of body temperature is a priority. Cool water (not cold) may be poured over the head, stomach, armpits and feet. Do not cover the dog with wet cloths, as this can prevent evaporative or radiative cooling. You can, however, mist cool water over the dog and place them in the path of a fan or air conditioning to promote cooling. Ice packs and rubbing alcohol are no longer recommended as a method to promote temperature reduction.
Once at the hospital, common treatments for heat stroke include intravenous fluids, mild sedation, and low-concentration oxygen therapy. The dog's rectal temperature will be monitored, and once the dog shows signs of recovery or their temperature falls to 103ºF (39.4ºC), treatment will be discontinued. If cooling is not discontinued, then the patient could develop hypothermia (dangerously low body temperatures).
What is the prognosis for heat stroke?
The prognosis for heat stroke depends on how high the body temperature elevated, how long the hyperthermia persisted, and the pet’s physical condition before the heat stroke. Most healthy pets will recover quickly if their body temperature does not become extremely high and if they are treated immediately.
Some pets may experience permanent organ damage or may die later from complications that developed secondarily to hyperthermia. Pets that experience hyperthermia are at greater risk for subsequent heat stroke, due to damage to the thermoregulatory center in the brain.
