With the weather remaining cold over winter, it is important to wrap up warm when we go outside. Those of you more familiar with colder climates may know the risk frostbite poses to humans. What about dogs? Is frostbite in dogs something you should be worried about too?

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What is Frostbite?

Frostbite is a condition caused by cold, wet and windy conditions. When it’s cold, the body constantly fights to stay warm, via methods like shivering, standing hair on end, and vasoconstriction (narrowing of blood vessels). If the body cannot produce enough heat, it will start to prioritise keeping the core body warm by vasoconstricting blood vessels in the extremities, such as the hands, feet, ears, nose, cheeks and genitals (and tails in dogs) – this results in less blood flow to these areas. This can lead to frostbite. Frostbite damage can occur through two mechanisms that can take less than 15 minutes. 

Firstly, as the tissue starts to get even colder, water in the body freezes forming ice crystals

Ice expands to fill a larger volume than water, so the ice damages cells and blood vessels. This directly kills cells, and results in even less blood flow and oxygen to an area. Lack of oxygen to a tissue is called ischaemia. Generally, the longer tissue remains frozen, the more irreversible damage will be done. Even when it is not cold enough for body-water to freeze, the body will cause cycles of vasoconstriction and -dilation to try and keep the extremities warm while still prioritising the core. These cycles increase the risk of blood clot formation that can block blood supply to the extremities. 

The second form of damage occurs when the cold areas are rewarmed in an unsafe way

As the tissue warms up and the blood vessels open up again, blood returns to the tissue.  However, rather than restoring function, due to ischaemia the tissue creates conditions that favour inflammation and further damage to cells, possibly resulting in more blood vessel damage and even more ischaemia. 

In extreme cases of frostbite, severe damage and ischaemia to tissue can result in death of the tissue (necrosis).

What Does Frostbite Do?

Frostbite in people (or dogs) initially causes cold, numb or tingly feelings in the skin, swelling and redness. ‘Pins and needles’ is a common feeling reported by people. A good warning sign is the skin looking blue or grey too. As the damage advances, the skin becomes blistered, ulcerated and black (necrosis). Skin at this stage is in an emergency state, and needs urgent care to prevent loss of the area. Untreated frostbite will lead to loss of tissue (loss of fingers, toes, ear-tips, tail-tips etc.). Frostbite on its own is rarely life-threatening, but damaged skin will also open the body up to serious infections, which can be.

Because the body is cold, frostbite is often seen alongside hypothermia, where the core body temperature drops dangerously low. This can present as shivering, lethargy, cold and pale skin, rapid breathing, collapse and eventually death. Hypothermia is life-threatening. 

What Dogs Are at Risk?

Any dog in below-freezing conditions is at risk of frostbite. The risk increases if their skin or fur is wet or it is very windy, as both of these can cause heat loss to accelerate. Smaller dogs, short-haired or hairless breeds, very young and very old dogs, and underweight or skinny dogs are at greater risk. Dogs with heart disease, diabetes mellitus and other circulatory conditions, or on drugs that reduce high blood pressure such as beta blockers, are at higher risk as their extremities are more vulnerable to ischaemia.

How Is Frostbite Diagnosed?

Frostbite is generally diagnosed based on history of exposure to cold, and a physical exam showing damage to tissue. Sometimes, blood testing may be performed to identify any underlying diseases like diabetes, or quantify inflammation. X-rays can also show how much underlying damage is present in tissue. If there are secondary infections, culturing the bacteria can help identify which antibiotics may be needed.

Treatment of Frostbite

As the owner, emergency first aid treatment of frostbite should initially involve getting your dog out of the cold and wet conditions immediately. However, if your dog is at risk of frostbite, so are you, so always prioritise human health first. Once your dog is out of the cold, their frostbitten areas should be gently warmed using body heat (such as human armpits if safe to do so), warm towels or blankets, warm (not hot) hot water bottles, or tepid water (no hotter than 40°c).

It is very important that warming is done gradually to avoid damage – never use hot water, radiators, fires or heaters. Do not rub the areas as this can damage the skin further. Remove anything damp they are wearing, like coats or collars, as these will cause more heat loss. Remember that hypothermia is also seen alongside frostbite, so wrap your dog’s whole body in warm towels too.

Regardless of severity, please ring your vet for advice and be prepared to visit once your dog is safe to travel

Severe frostbite requires immediate veterinary attention. At the vets, gentle warming will be continued. This can be enhanced via warmed intravenous fluids. Pain medication will also be given, as frostbite is often very painful for dogs. Topical or systemic antibiotics and antiseptics may be needed if infection is present. 

In extreme cases, necrotic and non-viable tissue may have to be removed to prevent spread to other parts of the body. This may require surgical debridement or even amputation of tissue. Because the dog is often not stable at the time, and necrosis can take a few weeks or months to develop, this is usually done at a later date. 

How to Prevent Frostbite

Despite the UK’s relatively temperature climate, frostbite should always be on your mind in cold weather, particularly if you have any of the at-risk dogs listed above. Try and walk them during the warmer parts of the day, or keep walks shorter. Never leave dogs outside in below-freezing temperatures with no protection. 

It’s a good idea to keep these dogs covered up more too, with coats and boots, especially when wet or snowy. This will also protect them from irritation from road grit. Just like in humans, layers are better than a single thick coat. After every walk, gently wash their paws with warm water to wash away debris, then dry them thoroughly. Some dogs may benefit from pad moisturiser to protect the skin too.

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