Ruff Guide Hypothermia Edition By Dr. Kim Smyth
Hypothermia The Cold Shoulder Edition
Mammals work very hard to the thermoregulate, or maintain a constant core temperature, which is vital to overall health. While these temperatures vary from species to species, they all fall within a very narrow range. For humans, it’s around 98.6 F and for our four-legged family members, it’s between 101.5F and 102.5 F
In cold temperatures, heat loss triggers the narrowing of blood vessels (vasoconstriction in the extremities in an effort to maintain core temperature. If vasoconstriction is not enough to regulate the body’s temperature, involuntary shivering begins. This extra muscle movement is an attempt to generate enough heat to return the body’s temperature to normal.
Hypothermia is the medical term used to describe a core body temperature that is below normal. In pets, that’s anything below 100.5 F. Hypothermia can occur as a result of heat loss, decrease heat production or problems with the thermoregulation system due to underlying disease.
Other factors affecting thermoregulation in our pets include age, body condition and the circadian rhythm( the body’s natural temperature cycle in a 24 hour period). There are two types of hypothermia.
- Primary Hypothermia: A direct function of the environment’s temperature, this type is usually accidental (like when a pet is exposed to cold weather for too long).
- Secondary Hypothermia: This type is caused by underlying issues, including sepsis, trauma, blood loss, shock and disease.
Almost every major organ and system is negatively affected by hypothermia. A slow heart rate means oxygen can’t effectively get to tissues. The colder the body becomes, the higher the chance of developing an abnormal heart rhythm. Liver and immune function both decrease while blood clotting times increase. Sever hypothermia can result in coma and death.
Freezing and sub-freezing temperatures also make frostbite a cancer. Frostbite occurs most often in the extremities (paws, ears, tail, and nose) as the body makes blood vessels smaller there to conserve core temperatures.
Signs and Symptoms
Clinical signs of hypothermia vary based on the severity of the condition. They range from
1. Decreased body temperature
3. Decreased heart rate
4. Stiff Muscles
5. Weakness/ Lethargy
6. Altered mental state (dull, stuporous)
Clinical signs of frostbite may not be evident for days after exposure to freezing or subfreezing temperatures. You may notice a white or blue-grey discoloration to tissues, along with pain, swelling and ulceration. Sever frostbite will result in tissue death; non-viable tissue turns dark or black in color and sloughs off.
Hypothermia is diagnosed based on physical exam findings and the pet’s health history. An animal presenting with a decreased rectal temperature is hypothermic, whether it be accidental or because of underlying medical conditions.
If your pet’s hypothermia is unrelated to the environmental temperature, your veterinarian will want to run bloodworm to check for diseases that could be behind the low body temperature.
Frostbite may be evident immediately, or it may take time to develop. Your veterinarian will diagnose frostbite based on clinical signs and a history of exposure to freezing temperatures.
If your pet is experiencing hypothermia, bundle them in warm blankets and proceed to your veterinarians office.
Your veterinarian will asses the severity of hypothermia and tailor treatment from there. Animals with severe hypothermia (< 94 F) will be unable to shiver or seek heat. In these cases externals sources of heat like circulating warm air devices (like BAIR huggers), hot water bottles, heated rice bags, and radiant heat lamps may be used.
For the most serious cases, invasive warming techniques including warm humidified oxygen therapy, warm intravenous fluids, or even warm abdominal or gastric lavage (rinses with sterile water) may be needed.
The treatment for frostbite will vary depending on the severity of the condition. Serious frostbite may require surgical removal of the dead skin and other soft tissues, or it may require amputation. Treatment of superficial wounds and pain will also be a part of managing any case of frostbite.
The prognosis for patients with hypothermia and/ or frostbite is variable. Some patients especially those with mild clinical signs on presentation, do well. Others whose core temperature has dropped to 94 F or lower may succumb to hypothermia.