Exposure to cold, rain, and snow can cause health problems for our dogs, such as hypothermia. Learn how heat loss affects your pet, the symptoms of hypothermia, and how to treat and prevent it.

Meteorological phenomena such as the storm Filomena and the frosts that have occurred in the days after the significant snowfall can constitute a risk for your pet. 

So it is essential to know the warning signs that indicate that the dog is losing heat and how you should take action to protect yourself from possible hypothermia and its consequences.

The first thing you should know is that the average temperature in dogs ranges between 37.5 ° C and 39.2 ° C, and the drop in body temperature below these physiological values ​​is called hypothermia. This situation can be dangerous for your health if it is not detected and solved in time.

Causes and Risk Factors of Hypothermia in Dogs

Dogs are warm-blooded animals, i.e., they can regulate their body temperature to keep it constant. The balance between the production of heat and its loss –what is known as thermoregulation– is achieved thanks to the action of the hypothalamus, which acts as a thermostat. Still, any situation that causes loss of heat or a decrease in its generation or alters the thermoregulatory capacity of the animal’s body can lead to a state of hypothermia.

We can classify hypothermia based on its origin:

  • Primary hypothermia: caused by heat loss due to prolonged exposure to low temperatures, especially in very cold or rainy climates. Animals lose heat from the body to the air (convection) or objects in contact with the skin (conduction).           
  • Secondary hypothermia: due to a failure in the production of heat or thermoregulation due to the action of anaesthetic drugs, surgical interventions, trauma, or diseases (kidney failure, alterations in the central nervous system, thromboembolism).

In addition, depending on its severity, hypothermia in dogs can be classified as mild, moderate, severe and profound, or critical.

The main risk factors that predispose dogs to hypothermia are:

  • Age:  puppies or older dogs (over ten years old).
  • Breed: short-haired and small-sized breeds, such as the Chihuahua.
  • Way of life: guard and defence, sledge or rescue dogs that spend a lot of time outdoors or in adverse weather conditions.
  • Diseases: hypothyroidism, kidney failure, hypoadrenocorticism.

How cold can a dog take according to its breed and size?

The risk dogs run when exposed to frigid temperatures depends on their breed and size. For example, the General Directorate of Animal Rights of the Government of Spain has published a climatic safety scale for dogs created by veterinarians from Tufts University, which determines the minimum temperature that dogs can withstand based on their size and breed.

The conclusion reached by these experts is that larger breeds are better prepared to withstand the cold and that while temperatures ranging between -1 ºC and four ºC would already pose “a risk” for certain species of small dogs and medium, in the case of the largest, this limit is between -4 ºC and one ºC.

They consider the “potentially dangerous climate” to be -4ºC for small dogs, between -4ºC and -9ºC for medium dogs, and -9ºC for large dogs. Temperatures below -6 ° C would be “critical” for small dogs, and the same applies to medium and large dogs exposed to -12 ° C.

When these conditions occur, animals should only stay outside for the necessary time to relieve themselves. Therefore, extreme precautions should monitor their condition while away from home and keep them warm.

Hypothermia in the dog

Symptoms of hypothermia in the dog and diagnosis

To understand how they occur and the symptoms that warn that a dog suffers from hypothermia, it is essential to know how the thermoregulatory mechanisms work in hypothermia in these animals. For example, when the temperature receptors located in the skin, abdominal organs, and blood vessels of the dog detect a drop in temperature, they signal the hypothalamus to compensate for the situation by producing heat.

First, the peripheral blood vessels that supply the outermost parts of the body contract. In this way, circulation is redirected to essential organs, such as the brain, heart, and liver, to continue to function. Second, muscle activity and metabolic rate are increased to generate calories. In addition, the hair stands on end (piloerection) to create a layer of hot air that insulates the skin.

Signs of hypothermia in the dog

In the initial stages, the dog will try to compensate for the situation by increasing muscle activity, which we will detect as tremors and chills, and piloerection, but this only works for a few hours, since this effort will end the energy reserves and the animal will present exhaustion, prostration, and hypoglycemia.

In addition, we will observe pale mucosa due to peripheral vasoconstriction. If hypothermia persists, a decrease in breaths per minute and cardiac arrhythmias will occur.

In the deep or critical phase of hypothermia, the animal will lose consciousness, multi-organ damage will occur and eventually die.

Diagnosis of hypothermia and assessment of the animal’s condition

Suppose we perceive tremors, piloerection, pale mucous membranes, or prostration in our dog. In that case, we must take the rectal temperature with a standard thermometer, preferably with a flexible tip, to check for hypothermia. If it is mild, we can warm the animal ourselves, but if it is moderate or severe, we must shelter it and contact the emergency veterinarian.

The veterinary professional will carry out blood tests to assess if there is damage to the internal organs, an electrocardiogram to monitor cardiac arrhythmias, and take blood pressure before starting to apply the most appropriate treatment depending on the severity of the pet’s condition.