Adder Bites in Pets: UK Snake Safety Guide

Recognising an Adder

The adder (Vipera berus) is a medium-sized snake, typically 50–65 cm in length, with a distinctive zigzag pattern running along its back and a V or X shape on the back of the head. Females tend to be brown with darker brown markings; males are typically grey or silvery with black markings. Adders can sometimes appear almost entirely black.

Adders are protected under the Wildlife and Countryside Act 1981 — it is illegal to kill, injure, or disturb them. They are shy and will bite only if they feel cornered, threatened, or are accidentally stood on or grabbed. Most adder bites to pets occur when a dog investigates or sniffs an adder at close range.

Where Adders Are Found

Adders are found throughout mainland Britain, from the south coast to northern Scotland, but not in Ireland. They prefer open habitats: heathland, moorland, chalk downland, woodland clearings, embankments, and coastal areas. They are particularly associated with gorse, bracken, and bramble patches where they can bask and hunt.

Adders are cold-blooded and need to warm up in the sun — they are most likely to be encountered basking in the morning on warm, sunny days in spring and early summer. They hibernate from October to February and are not active in cold weather.

Symptoms of Adder Bite in Dogs

Symptoms of adder envenomation usually appear within 15 minutes to a few hours of the bite. Common signs include sudden swelling at the site of the bite (most often on the face, nose, or front legs of a dog), pain and yelping when bitten, two small puncture marks (sometimes visible but not always), lethargy and weakness, vomiting, and pale gums.

In more severe cases — which are more likely if the bite is close to the face or throat, if the dog received a large venom dose, or if the dog is small or has underlying health conditions — you may see severe swelling affecting the airway, cardiovascular collapse, clotting problems (bleeding from the gums or bite site), tremors, and in rare cases, coma.

Do not wait for severe symptoms before seeking help. Most deaths from adder bites occur in untreated animals, and early treatment significantly improves outcomes.

What to Do If Your Dog Is Bitten

Keep your dog as calm and still as possible — movement increases the circulation of venom through the body. Carry your dog rather than letting it walk if you can. Contact your vet immediately and tell them you suspect an adder bite. If the bite is clearly on the face or near the throat and swelling is progressing rapidly, this is an emergency — go directly to an out-of-hours emergency vet if your regular vet is closed.

Do not attempt to suck out the venom — this does not work and can cause harm. Do not apply a tourniquet. Do not cut the wound. Do not give any medications unless instructed by your vet.

Treatment at the vet may include intravenous fluids to support blood pressure, anti-histamines and corticosteroids to reduce swelling and allergic reaction, pain relief, and in severe cases, antivenom (Zagreb antivenom is available at some UK veterinary practices).

Preventing Snake Encounters

Keep your dog on a lead in known adder habitats, particularly in spring when snakes first emerge and are slower to move away. Teach a reliable recall so you can call your dog away from suspicious areas. Stick to clear paths where you can see where you and your dog are stepping. In long grass and gorse, stamp your feet or make noise as you walk — adders will usually move away from vibrations.

If you see an adder, back away slowly and calmly, and encourage your dog to do the same. Never attempt to handle, kill, or interfere with an adder — this is both illegal and dramatically increases the risk of a bite.