Adder bites on dogs

Britain has 3 native snakes: the Adder or Common Viper, grass snake, and smooth snake, but only the Adder is venomous.

Growing to between 60 & 80cm, Adders are a slight, shy creature with a red eye, and striking, dark, zigzag patterning down their backs although, occasionally, they are black.

Hibernating between October and March, you are most likely to come across them sunbathing in their moorland, heathland or woodland habitat, or even your garden, between April and September. This is the window during which most snake bite claims are made.

Adder bite symptoms

It is not always clear that your dog has been bitten by an Adder. Your dog might be some way off and disturb one which disappears before you arrive. And your dog may not react to being bitten immediately, so keep an eye out for the following symptoms:

Pain, redness or bruising
Bite marks - 2 small puncture wounds 6-9mm apart
Sudden tiredness and wanting to lie down
Generally seeming out of sorts
Swelling at the site, within an hour, sometimes becoming severe
Vomiting and diarrhoea
Sudden nervousness

First Aid

Do NOT try to treat your dog yourself, this can make things worse.

What you can do:

Keep calm and try to keep your dog calm.
Pick up and carry your dog or, if they are too big, walk them calmly and slowly to your car or home.
Call your vet to let them know you are on your way, and take your dog there immediately.

Allowing your dog to continue exerting themselves increases the rate at which the venom is spread throughout your dog’s body. Keeping them calm and as still as possible is the best way to limit this.

Complications

Depending on how much venom was injected by the snake, your dog’s blood pressure and circulation, or the natural rhythm of your dog’s heartbeat, may be affected. And your dog may also suffer from soft tissue damage, or damage to their internal organs.

Treatment

On arrival at the vet, your dog will be given fluid therapy via a drip, to help maintain their blood pressure, prevent shock and support their vital organs. Adder bites are often very painful so your vet will also administer painkillers and antihistamine to help reduce the swelling and make your dog more comfortable. In severe cases, your vet might want to give your dog Adder anti-venom. This binds with the venom so that it becomes inactive and can’t cause any further damage. However, it is not easy to get hold of and not all vets stock it. It can be a case of ringing around local vets to find one with stock and an emergency dash to collect it.

Being bitten by an Adder is always a medical emergency with risk of serious illness and even death but, with prompt treatment and supportive care, most dogs go on to make a full recovery.

Protected species

Adders are a protected species in the UK and, under the Wildlife Act of 1981, it is illegal to intentionally kill or injure Adders, or to trade in them. If your dog has been bitten by an adder, it will be because the Adder was startled or trodden on, and acted in self-defence. Do not try to catch the suspected snake, Adder bites are actually quite rare, with only about 100 being reported every year; better to leave it alone to slither away and hide, while you focus on getting your dog the veterinary care they need.

Written by: Samantha Khan
Last reviewed on: 23 June 2026

About the Author

Sam Khan shares her woodland home with Junior, the cat, Gully, the dog and bunnies Hugo & Billy, sometimes playing the family’s ‘favourite’ game with the tortoise – “Where’s Churchill?” She loves writing for Agria, sharing our passion for animal welfare, protecting biodiversity and the environment. When not writing or illustrating, she will be making something, reading a book or swimming in the lake at the bottom of her lane.