Medical Jargon Explained: Hypo- Versus Hyperthermia

Balance is a foundation of a healthy dog, whether it is a balance between work and play, exercise and rest, a balanced diet, or balance within the body itself.

Disruptions in balance can result in behavioral problems or disease.

Every imbalance can present itself as either a deficiency or excess. 

The above prefixes describe these two extremes. Hypo- stands for deficiency, while hyper- indicates excess. Neither of them is a good news, though deficiencies are often easier to deal with as long as an effective supplement is available.

Hypothermia versus hyperthermia

These are terms we are all familiar with. They refer to abnormal body temperatures. Both severe hypothermia and severe hyperthermia can be lethal to your dog. A dog's normal body temperature ranges between 100.5 Fahrenheit (38.1°C)  and 102.5 Fahrenheit (39°C).

Temperatures below 99 degrees Fahrenheit (37.2°C) and temperatures above 104 degrees Fahrenheit (40°C) are considered extremely serious and you should bring your dog to a veterinarian immediately.

Of course, if your dog is acting abnormally, you should take him to the veterinarian regardless of what the thermometer reads.

When your dog's body temperature drops below normal, it is referred to as hypothermia. This can occur as a result of prolonged exposure to cold temperatures. Remember that damp or windy conditions make cold conditions even more dangerous for dogs. Severe hypothermia can lead to death. The good news is that with a little common sense and diligence environmental hypothermia is easy to prevent.

Some breeds are more sensitive to cold temperatures, particularly small dogs and dogs with a single coat.

Dogs that are suffering from a severe illness (e.g., kidney failure) may also develop hypothermia, even if the air temperature is warm.

Symptoms of hypothermia are
  • shivering, although shivering stops when hypothermia becomes very severe
  • lethargy
  • muscle stiffness
  • lack of coordination
  • low heart and breathing rates
  • fixed and dilated pupils
  • collapse
  • coma

Hyperthermia/heatstroke, on the other hand, refers to body temperatures above the normal range.

There are many horror stories about dogs suffering extreme hyperthermia when left alone in a car. The outside temperature doesn't even have to be that high for the interior temperature to rise enough to harm your dog. Please keep that in mind and do not leave your dog in a car unattended.

However, even when your dog is outside, a combination of hot weather, exercise and dehydration can lead to a heatstroke.

Some breeds such as bulldogs, pugs and boxers are particularly at high risk of heatstroke because of an inability to pant effectively.

There are other causes of hyperthermia in dogs, including drugs. Jasmine suffered bad hyperthermia as a result of a reaction to a Buprenorphine injection. Her temperature shot up to 42.5°C within minutes. Even though immediate steps were taken to get her temperature back down, she suffered damage to the platelets in her blood and to her muscles. She was in such bad shape that she wasn't able to get up or walk on her own for a week. This is how bad even short-term hyperthermia can be.

Symptoms of hyperthermia are
  • Rapid panting
  • Bright red, purple or Blue mucous membranes (e.g., the gums)
  • Thick, sticky saliva 
  • Drooling
  • Depression
  • Weakness
  • Dizziness
  • Shock
  • Coma

First aid steps are quite logical. Warm the hypothermic dog and cool the dog suffering from heatstroke. Both severe hypothermia and severe hyperthermia are emergency situations and require immediate medical care so it is best to provide first aid as you are transporting your dog to a veterinary hospital.

To warm a hypothermic dog, move him to a warm area, lay him on and cover him with blankets that have been warmed in a dryer first if possible.  Place a hot water bottle or two under the blankets next to his body, but make sure the bottles are not so hot that they could cause burns.

To cool a hyperthermic dog, move him to a cool and shaded environment and direct a fan over his body.  Spray cool (not cold) water or rubbing alcohol on sparsely haired parts of the body (e.g., foot pads, armpits, and groin). Do not use ice or ice water to cool a hyperthermic dog.

Remember, the best treatment is prevention. Keep an eye on your dog and save yourself the heartbreak.

Related articles:
Know Your Dog's Enemies: Heat Stroke Is No Light Matter!