In this article
Your dog noses into the heather, jumps back and looks at you. Perhaps you saw a snake. Perhaps you only notice a swollen muzzle when you return to the car. It is an unsettling situation, especially somewhere unfamiliar, with the car park suddenly feeling a very long way away.
If you suspect a snake bite, call your vet immediately and keep your dog still while arranging transport. You do not need to identify the snake before seeking help1.
There are two useful things to take from this guide: a short response you can remember under pressure, and enough background to put the risk in perspective before your next walk. Read the practical steps first if something has happened today.
What to do in the first few minutes
Focus on getting help, without doing more to the bite. A phone call gives the practice time to prepare and lets you explain where you are. PDSA advises leaving the wound alone, avoiding bandages and tourniquets, and bringing the car to your dog or carrying them if possible1.
A short response to remember
It helps to have one person make the call while another stays with the dog, if company is available. Describe what you saw in your own words. “He sniffed something, jumped back and his lip is swelling” is a useful account; you do not have to arrive with a diagnosis.
Where an encounter is more likely
Adders favour sheltered, sunny places. Amphibian and Reptile Conservation lists long grass, deep heather, gorse and bramble edges, and stone walls as places dogs may investigate. A dog sniffing or pawing at a snake can provoke a defensive bite. Keeping close control in these patches is a sensible precaution2.
The same charity stresses that bites are rare beside the enormous number of countryside visits. That is a reason to prepare calmly, rather than abandon favourite outdoor places. If an adder is on the path, leave plenty of space, wait for it to move or choose another route; do not try to shoo it away2.
One historical UK study gives a seasonal clue. Researchers reviewed Veterinary Poisons Information Service cases with follow-up from September 1985 to December 2010. In that series, 69.2% of bites occurred from April to July, with a peak between 15:00 and 16:00. These are reported clinical cases, not a timetable that makes other months or mornings safe5.
Think of a lead as a little extra supervision at the point where your dog disappears nose-first into vegetation. You can still build a lovely outing around the visible path, a picnic spot and a route everyone finds manageable. The aim is to make a local decision, not turn every rustle into a snake.
What a bite can look like
A 2024 European veterinary review describes swelling, pain, lethargy, fang marks, vomiting and diarrhoea among signs reported after adder bites. Some dogs develop problems beyond the bite site, including changes involving the heart. The amount of visible swelling cannot give an owner a reliable home severity score6.
You may never see the snake. ARC explains that signs can take time to become apparent and can resemble other causes of illness. The location, what your dog was doing and how the signs developed all help the vet assess the possibilities. Suspicion is a reason to seek assessment; it is not proof of what caused the swelling2.
Avoid treating a photograph online as a diagnostic test. In the UK case series, initial effects usually appeared within two hours, and roughly a third of dogs had local effects alone. Those observations describe the study group. They cannot tell you that an individual dog with a swollen paw will remain otherwise well5.
Make your account chronological: where you walked, when anything unusual happened, what you first noticed and what has changed since. If someone else witnessed the encounter, ask them to give their account too. An uncertain detail is better described as uncertain than tidied into a story that sounds more definite.
Why the vet may want to keep your dog in
In a prospective Swedish study, 53 dogs were examined after suspected or observed adder bites. All had swelling, and no dog died during follow-up. Yet six developed heart abnormalities at the second examination despite normal initial heart listening. That helps explain why an encouraging first impression does not always end the investigation3.
The study followed dogs over several examinations, with fewer dogs available at later visits. It was small, undertaken at two hospitals and cannot establish how every UK dog will fare. Its practical message is narrower: complications may emerge after presentation, and follow-up can provide information that a single examination misses3.
VPIS describes the course of adder poisoning as variable and unpredictable. Its veterinary service helps practices obtain antivenom when required. The treatment decision belongs with the attending vet, who can assess the whole dog and seek specialist poison advice; it is not something an owner can settle from the snake's size or the appearance of the wound7.
Ask what the team is watching for, when they expect to update you and what the next decision will be. Those questions are often more helpful than asking for a guaranteed recovery time. They also give you something concrete to write down while you are worried and taking in unfamiliar information.
What recovery figures do and do not mean
The older UK series reported 4.6% mortality among the cases it studied. It was a retrospective poison-service series with follow-up, not a random sample of every dog bitten in Britain. Its recovery and treatment observations should not be converted into a personal prediction or used to justify waiting at home5.
The European review found limited published evidence and differences between reports. It also notes that some UK cases occurred during cooler months. A useful reading of the research is that outcomes depend on the case and the evidence remains incomplete, while prompt professional assessment is still the practical response6.
There is room for reassurance without a promise. VPIS characterises deaths as relatively uncommon but illness as potentially substantial. It also describes antivenom access support for vets. That is encouraging background for an owner who has made the call; it is not a reason to spend time sourcing medicines yourself before the dog has been assessed7.
Sharing the countryside with adders
NatureScot describes adders as elusive animals whose usual defence is to hide. Bites, including those involving pets, are largely associated with disturbance. Leaving a snake alone and allowing it to move away quietly protects both the dog and the wildlife. There is no need to catch it or bring it to the practice4.
In Scotland the adder is the only native snake. NatureScot also encourages reporting sightings through wildlife recording schemes. A sighting can be an interesting part of understanding your local countryside when everyone is safely apart; it need not become an encounter at close quarters4.
Before a trip, put the vet's details alongside your route and parking information. Then let the walk be a walk. A little preparation is there to free up your attention for your dog, the path and the good parts of being outside.
Sources and further reading7 sources
The small numbers in the article link to the source behind each fact. Sources open on their own websites.
- Snake bites in dogs
- Facts and advice on adder bites
- Clinical and biochemical changes in 53 Swedish dogs bitten by the European adder - Vipera berus
- Adder
- Canine adder bites in the UK: a retrospective study of cases reported to the Veterinary Poisons Information Service
- Zootoxins and Domestic Animals: A European View
- Adders and antivenom