Causes of Canine Heat Stroke
Heat stroke, also known as hyperthermia, is a true medical emergency. Dogs don’t tolerate high environmental temperatures as well as most other mammals do because dogs don’t sweat, except to a very small degree through their paw pads. Dogs can only dissipate body heat by panting, which helps them exchange hot air from their inside for cooler air from the outside. When external temperatures are close to or higher than a dog’s internal body temperature (normally between 101 and 102 degrees Fahrenheit), even panting won’t really help a dog cool down.
Heat stroke can be caused by anything that elevates the core body temperature. One cause of heat stroke in dogs is abnormal muscle fasciculations, which are involuntary spontaneous contractions of muscle fibers that generate a lot of body heat. Muscle fasciculations can be triggered by epilieptic seizures, low circulating levels of blood calcium (hypocalcemia), ingestion of mycotoxins (commonly found in rancid garbage) or ingestion of metaldehyde (the active ingredient in many pelleted slug and snail baits). More frequently, heat stroke happens when a dog is exposed to excessively high environmental temperatures for a prolonged period of time, or when a dog can’t disseminate heat from its body as well as it should. This is especially common in dogs that are overweight, dogs left in closed cars and those that have been exercised vigorously on a hot day. When a dog’s core body temperature rises, its regular responses to inflammation become impaired, and tissues and organs start to die.
Situations and conditions that contribute to heat stroke in dogs include:
- Confinement without adequate shade and water in hot weather
- Vigorous exercise in hot weather
- Confinement in a car or other enclosed area in hot weather
- Confinement on asphalt or concrete without shade or a way to get off of those surfaces
- Being muzzled while restrained under a hair dryer (especially in a drying cage)
- Being very young or very old
- Having upper airway obstruction
- Being a member of a brachycephalic breed, such as the Pug, Pekingese, Bulldog, Boston Terrier, Boxer or Cavalier King Charles Spaniel; these dogs have flat, “squashed in” faces and broad top skulls, which predispose them to respiratory problems
- Cardiovascular (heart), pulmonary (lung) or other diseases that interfere with efficient breathing and oxygen exchange
Preventing Heat Stroke
Dog owners should familiarize themselves with the signs and causes of heatstroke, which is a potentially fatal condition. Dogs should always have free access to clean, fresh water and shade, especially in hot weather. They should never be left in a car with the windows closed or slightly ajar, even if the car is parked in the shade and the owner is only planning to be gone for a few minutes. Dogs with preexisting respiratory disease or breathing problems should be kept indoors with a floor fan or air conditioner running when the weather is hot and humid. No dog should be exercised strenuously in hot weather. Dogs should not be confined on concrete or asphalt without some way to get off of those heat-attracting surfaces. Dog beds, blankets, mats, wooden planking and grass all stay cooler than asphalt and cement and are kinder to a dog’s sensitive feet.