Everything Owners Need to Know About Hypothermia In Dogs

When it comes to health concerns related to your dog, getting too cold may not be at the top of your mind. 

During winter, or the cooler months,  it's important to be aware of the health risks related to cold weather for your dog. Living in Australia, you wouldn't think Hypothermia in dogs was a common issue. However, your dog can suffer from mild hypothermia when their body falls below just 37°C! 

Rewarming shock is a common adverse complication resulting from blood vessel dilation when the extremities are warmed before the core. Knowing potential causes, symptoms, and how to warm up your dog safely can ensure you take quick action in case your dog's temperature ever starts to drop.

What is Hypothermia in Dogs?

Hypothermia is a medical condition where a dog’s core body temperature drops below the threshold that their natural temperature (38.3 to 39.2°C) regulation system can respond to.

This means that a dog’s internal temperature cannot be raised by the standard bodily mechanisms, resulting in a risk of damage to the dog’s health and potentially can become life-threatening.

What Body Temperature Is Safe & What Is Too Low for Dogs?

Dogs’ core temperatures naturally run higher than ours. The normal body temperature for a dog is 37.5 to 39.2°C. This can lead to some confusion for dog owners because a dog’s low temperature threshold does not seem ‘too cold’ by human standards.

A drop in a dog’s body temperature to just 37°C or lower indicates the start of hypothermia.

The Most Common Causes of Dog Hypothermia

Understanding what causes dog hypothermia enables dog owners to be vigilant in recognising and avoiding dangerous conditions. To prevent your dog from possible hypothermia, be mindful of their temperature.  

• Prolonged Exposure to Cold: Dogs left outside for extended periods, especially without proper shelter or insulation, are at high risk.

• Wet Fur in Cold Weather: Wet fur loses its insulating properties, making dogs more susceptible to the cold. This can happen after swimming, bathing, or being caught in the rain or snow.

• Inadequate Shelter: Dogs without access to warm and dry shelters, especially at night, are more likely to develop hypothermia.

• Health Conditions: Dogs with underlying health issues, such as dehydration from diarrhoea, or conditions like diabetes, Cushing’s Disease, heart disease, or poor nutrition, may have impaired thermoregulation, increasing their risk.

• Age and Breed: Puppies, senior dogs, and breeds with thin coats or low body fat are more vulnerable to the cold.

How does Hypothermia Occur? 

Hypothermia occurs when a dog's body temperature drops significantly below normal levels, impairing bodily functions. Here’s a breakdown of how hypothermia works: 

• Heat Loss: Dogs lose body heat through radiation, convection, conduction, and evaporation. In cold environments, these processes can exceed the body's ability to generate heat, leading to a decline in core body temperature.

• Physiological Response: In response to cold, a dog’s body initially attempts to maintain its temperature through shivering, which generates heat. Blood vessels near the skin constrict to preserve core warmth and redirect blood away from areas that can cause further cooling (ears, feet, legs) to areas necessary to sustain life (essential organs, like the heart, brain, liver). 

Progression of Symptoms:

• Mild Hypothermia: Begins with shivering, increased heart rate, wobbly gait (ataxia) and pale extremities (32-37°C).

• Moderate Hypothermia: Dogs may become lethargic and disoriented with a decreased level of consciousness. They may or may not be shivering and breathing, and their heart rate may slow down (28-32°C).

• Severe Hypothermia: Shivering stops as muscles become rigid, and the dog can become unconscious due to profound central nervous system deficits. At this stage, the body prioritises vital organs, further reducing blood flow to extremities and causing abnormal heart rhythms (<28°C).

• Impact on Body Functions: As hypothermia progresses, enzymatic reactions and metabolic processes slow down, impairing the function of organs and systems. This can lead to blood clotting abnormalities, organ failure, and central nervous system shutdown if not promptly addressed.

Signs of Hypothermia in Dogs

Hypothermia in dogs occurs when their body temperature drops to 37.0°C or below. The normal temperature of a dog ranges between 37.5 and 39.2°C. Recognising the signs and taking prompt action is crucial.

Mild Hypothermia:

• Shivering: The dog may shake to generate heat.

• Cold ears and paws: Extremities may feel cold to the touch.

• Lethargy: The dog may seem unusually tired or slow.

• Whining or anxious behaviour: Signs of discomfort.

Moderate Hypothermia:

• Weakness: The dog may struggle to walk or stand.

• Muscle stiffness: Movements become stiff or awkward.

• Slow, shallow breathing: Breathing rate decreases.

• Confusion or unresponsiveness: The dog may appear dazed or not respond to commands.

Severe Hypothermia:

Further progression into severe hypothermia is marked by the dog’s inability to regulate their temperature at all:

• No shivering: The dog stops shivering as muscles fail.

• Very weak pulse: Heart rate slows significantly.

• Collapse: The dog may become unconscious.

• Dilated pupils: Pupils may not respond to light.

Once progressed hypothermia has set in, a dog is at risk for organ failure, coma, and even loss of life.

How Can You Confirm That Your Dog Has Hypothermia?

Your vet is always the first and most important resource to contact when any pet emergency occurs, including potential hypothermia. We also suggest always having a thermometer in your Pet First Aid kit at home, so you can check their temperature yourself! 

How to Respond If You Believe Your Dog Is Hypothermic

Treatment of hypothermia requires external warming to bring the dog’s core temperature back up to a safe level. 

To Safely Warm a Dog with Hypothermia:

• Move to warmth: Get the dog indoors or into a warm environment.

• Dry thoroughly: Use towels to gently dry the dog if it is wet.

• Wrap in blankets: Use warm (not hot) blankets. A quick zip in the dryer can help warm them up.

• Use warm packs: Place a warm 38.5°C (not hot) wheat pack wrapped in towels near the dog’s body, not the extremities. Never fill hot water bottles with boiling water or place them in the microwave, as this risks serious burn injuries to dogs (in fact, it’s safest not to use hot water bottles at all). 

• Continue to monitor your dog's body temperature and seek veterinary care until it reaches 37°C, then stop re-warming. 

• Seek veterinary care: Always contact a vet for guidance and treatment to ensure appropriate supportive care is provided and to reduce the risk of rewarming shock.

How do Vets Treat Hypothermia?

Veterinarians treat hypothermia in dogs by gradually raising the dog's body temperature and addressing any associated complications. Initially, they check the dog's vital signs, including temperature, heart rate, and breathing, and perform a physical exam to assess the severity of hypothermia and any related issues.

To gradually rewarm the dog, they place it in a warm, draft-free environment and wrap them in warm blankets. Heating devices, such as forced-air warming units, are used in conjunction with warming blankets to circulate warm air around the patient, with careful monitoring. Heat pads and hot water bottles are rarely used in veterinary medicine because of the risk of burns and overheating. 

In severe cases, internal warming methods such as warm IV fluids, warm water enemas, and warm, humidified oxygen are employed to increase the core temperature and aid breathing.

What do vets monitor for while re-warming a patient?

Throughout the treatment, the dog's vital signs are continuously monitored, and oxygen therapy may be provided if needed. Fluids and electrolytes are administered to correct dehydration or imbalances. If there are underlying causes, such as infections, antibiotics are given, and any physical injuries are treated.

What is rewarming shock?

Veterinarians will also closely monitor for signs of rewarming shock, a serious complication that can occur during treatment. As a dog’s body temperature rises quickly, blood vessels suddenly dilate and place extra strain on the circulatory and metabolic systems. This, combined with the other demands from hypothermia and concurrent disorders, can be very dangerous while warming dogs in an already fragile state.  For example, the returning colder blood carries lactic acid with it to the core, also causing a blood acidosis. 

What is a safe rate of rewarming for dogs?

Some caution is necessary when applying heat to the trunk of the body rather than the extremities (e.g., legs), and it is best to avoid rewarming patients too rapidly. A steady rewarming rate of approximately 0.5 to 2.0°C per hour is usually what veterinarians in a hospital setting aim for. 

After the initial treatment, the dog may be kept under observation to ensure stability. Vets also provide guidance on gradually reintroducing normal activities and ensuring ongoing warmth at home to support the dog's full recovery.

It's Not Cool for a Dog to Get Too Cold

Hypothermia in dogs is not very common. However, when it occurs, it can be life-threatening. It's always best to prevent hypothermia, so remember to keep your dog indoors when the weather is its coldest. And should you worry that your dog does have hypothermia, wrap them in a warm blanket and immediately contact your vet.