HEAT STROKE AND HYPERTHERMIA
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, it is considered abnormal or hyperthermic. Body temperatures above 106°F without previous signs of illness are usually associated with exposure to excessive external or environmental heat. The critical temperature where multiple organ failure and impending death occurs is 109°F.
What causes heat stroke?
- The most common cause of heat stroke or hyperthermia is leaving a pet in a car or other area with inadequate ventilation. Your pet’s body temperature in this situation can elevate very rapidly, often within minutes. Dogs and cats cannot control their body temperature by sweating as humans do, since they only have a relatively small number of sweat glands located in their footpads, their primary way of regulating body heat is by panting.
- Being left in a yard without access to shade or water on a hot day.
- Being exposed to a hair dryer for an extended amount of time.
- Excessive or vigorous exercise during hot temperatures. Excited or excessively exercised pets are sometimes at risk even if the environmental temperature and humidity does not appear hot.
- Dogs with a restricted airway such as the brachycephalic breeds (flat faced dogs such as pugs, boxers, and bulldogs) are at greater risk. In these breeds, clinical signs of heat stroke can occur when the outside temperature and humidity are only moderately elevated.
- 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 are the signs of heat stroke?
Signs of heat stroke are very similar to the signs seen in humans, although dogs pant more in an effort to cool themselves.
- Hypersalivation (drooling)
- Warm to touch
- Red mucous membranes of mouth
- Rapid heart rate
- Dry nose
- Quiet or poorly responsive, may lay down and refuse or be unable to rise
- Blood from mouth or in stool
- Muscle tremors
- Ataxia (staggering)
What is the treatment for heat stroke?
Hyperthermia is an immediate medical emergency, seek medical attention for your pet right away. Safe, controlled reduction of body temperature is a priority. Cool water may be poured over the head, stomach, underarms and feet, or cool cloths may be applied to these areas. Rubbing alcohol may be applied to the footpads to dilate pores and increase perspiration. Ice may be placed around the mouth and anus.
The pet’s rectal temperature should be monitored, and treatment discontinued once the pet shows signs of recovery or the temperature has fallen to 103ºF.
What is the prognosis for heat stroke?
The prognosis depends on how high the body temperature elevated, how long the hyperthermia persisted and what the physical condition of the pet was prior to the heat stroke. If the body temperature did not become extremely high, most healthy pets will recover quickly if they are treated immediately. Some pets may experience permanent organ damage or may die later from complications that developed secondarily to the hyperthermia. Pets that experience hyperthermia are at greater risk for subsequent heat stroke due to damage to the thermoregulatory center.