There are few things better than a wild swim on a warm afternoon. Except, perhaps, a wild swim with your dog bounding in alongside you, ears flying, tail going like a propeller. It’s joyful, it’s wholesome, and — with the right preparation — it can be completely safe.
But wild water is not a paddling pool. Before your dog so much as gets their paws wet, there are a few things worth knowing.
Not Every Dog Is a Natural Swimmer
Most dogs have an instinctive ability to paddle when placed in water. This “doggy paddle” is a basic stroke that helps them stay afloat — but just because a dog can paddle doesn’t mean they’re confident or capable swimmers.
Retrievers and Spaniels are known for their strong swimming skills, thanks to their history of working in water environments — but other breeds may struggle and need encouragement and training. Flat-faced breeds, short-legged dogs, and heavily muscled dogs are often poor swimmers and can tire quickly in open water.
Start slowly. Let your dog wade in from a gently sloping bank, build confidence gradually, and never force them in. Make sure your dog is a confident swimmer with reliable recall before letting them go for a splash.
Choosing the Right Spot
Picking your swim location is arguably the most important decision you’ll make. Here’s what to look for — and what to avoid.
Look for calm water with a gradual entry and exit point. Avoid fast-flowing rivers, weirs, and deep reservoirs. Gradually sloping beaches or banks are best — your dog needs to be able to get themselves out without your help.
Canals and reservoirs have low visibility and may have hidden dangers below, like rusty trolleys, fly-tipped rubbish, or fallen trees. Also make sure the water has a solid bottom — not a mud bottom. You can get sucked into the mud and be unable to get out, which can be highly dangerous.
Always check whether dogs are permitted. Some rivers, ponds, and lakes do not allow wild swimming of any kind — restrictions could be in place for your dog’s safety, or the safety of wildlife.
The Blue-Green Algae Risk: Take This Seriously
This is the one that every dog owner swimming in UK fresh water needs to understand. Blue-green algae, or cyanobacteria, are a group of bacteria that can contain dangerous toxins which can be harmful and potentially fatal to pets, livestock, and birds if ingested even in small quantities.
In summer and early autumn — typically May to September — UK lakes, ponds, gravel pits, canals, and slow-moving rivers can develop blooms. Blooms often look like green paint or scum on the water’s surface, sometimes with a blue or grey tint.
Dogs can swallow it by drinking water from an affected lake, river, or pond, or while licking their fur after going for a swim. Symptoms can appear within a few minutes or hours of exposure and commonly include vomiting, diarrhoea, drooling, disorientation, trouble breathing, seizures, and blood in faeces.
“While not all blue-green algae are poisonous, it is impossible to tell the difference visually” — and there is currently no known antidote for the toxins, so prompt veterinary treatment is essential. If you see any suspicious scum, foam, or surface discolouration: don’t swim, and keep your dog well back from the water’s edge.
Download the Bloomin’ Algae app (from the UK Centre for Ecology and Hydrology) before you head out. You can report sightings of suspected blue-green algae with a photograph and set up notifications for confirmed sightings in your area.
Leptospirosis — Vaccinate Before You Swim
Leptospirosis can be spread through infected rat urine — dogs should be vaccinated against it and avoid high-risk areas. Dogs can be exposed through water or soil contaminated by the urine of infected animals, particularly rats, and slow-moving or stagnant water can be a risk.
Vaccination is an important part of reducing the risk. Speak to your vet about your dog’s vaccinations and boosters, especially if your dog regularly swims or explores areas with standing water. Don’t assume a vaccine covers everything, though — it’s a risk reducer, not a green light for any water.
Cold Water Matters for Dogs Too
If the water is too cold for you, it’s too cold for your dog. Your dog might willingly swim in water below 10°C, but it can still cause hypothermia. Small dogs, lean breeds, and older dogs are particularly vulnerable. Watch for shivering, lethargy, or clumsiness in the water — these are signs to get them out and warm them up.
Dry them off thoroughly after every swim, and pack a dog towel and an extra layer for them just as you would for yourself.
Key Safety Checks Before Every Swim
- Scan the water for surface scum, foam, or unusual colour — if in doubt, stay out.
- Check the Bloomin’ Algae app and local Environment Agency or Surfers Against Sewage alerts for water quality.
- Assess the entry and exit points before your dog goes in — check there’s an easily accessible exit point.
- Currents can be hidden and surprisingly strong. Only let your dog swim in calm waters and watch for any changes in conditions, including tide changes.
- Keep watch at all times. Dogs can’t bark while they’re swimming, so stay alert, stay close, and be ready to react.
- Rinse your dog thoroughly with clean water afterwards to remove any potential contaminants, and regularly check for cuts, abrasions, or signs of illness after a swim.
- Bring fresh drinking water — this stops your dog gulping from the swim spot, whether that’s a river, lake, or the sea.
Consider a Canine Buoyancy Aid
For extra security, you can use a flotation vest to support your dog. Make sure it fits properly and put it on before they enter the water. For small dogs, opt for one with a top handle so you can lift them easily if things go sideways. They’re not just for nervous swimmers — they’re great peace of mind for any dog in open water.
The Bigger Picture
The numbers here are worth knowing. RNLI data recorded 308 dog-related incidents between 2021 and 2025 — that’s over one incident per week on average, with around one-third occurring during the summer months. Many of these happen because owners assume familiar water is safe, or that a strong dog will always be fine.
None of this should put you off. Wild swimming with a dog is one of life’s genuine treats. But a little homework before you go — checking the water quality, knowing your exit, and keeping your dog’s vaccinations up to date — makes all the difference between a glorious afternoon and a terrifying one.
Do the prep, read the water, and then enjoy every single second of it together.