Of all the seasonal hazards I mention to clients, blue-green algae is the one I am most blunt about, because it is one of the few that can kill a dog within hours. It has been confirmed on Yorkshire reservoirs, including Grimwith near Grassington, and City of York Council has issued warnings about it too. If your dog loves water, this is worth taking seriously, so here is the honest version: what it is, how to spot it, and why you should not take any chances.
The frustrating part is that it can look like nothing much: a bit of green scum on the edge of a reservoir or pond. But some blooms release toxins that attack the liver and nervous system, and there is no antidote. The good news is that avoiding it is entirely within your control once you know what you are looking for.
What blue-green algae actually is
Despite the name, blue-green algae is not really algae at all. It is a group of bacteria, called cyanobacteria, that live in fresh water: reservoirs, lakes, ponds and slow-moving rivers. In warm, still, nutrient-rich water they multiply rapidly and form a bloom.
That bloom can look like:
- A blue-green, green or brownish scum on the water's surface
- Foam or a paint-like film gathered at the edges
- Pea-soup coloured water, or clumps floating just under the surface
Crucially, wind pushes the bloom to the edges and shallows, which is exactly where a dog paddles, drinks and shakes off. So a dog can be exposed without ever swimming out. Vets Now has a clear rundown of how it forms and why it is so dangerous.
Why it is so dangerous to dogs
Not every bloom is toxic, but you cannot tell by looking, so every bloom has to be treated as if it is. The toxins fall into two broad camps: ones that hit the nervous system and ones that damage the liver. A dog can swallow them by drinking the water, or simply by licking algae off its coat after a paddle.
Signs of nerve toxins can appear within minutes. Signs of liver toxins may take a few hours. Left untreated, exposure can lead to liver failure and death within a matter of days, sometimes far quicker.
Vet note: There is no antidote for blue-green algae poisoning. Treatment is about supporting the dog and limiting the damage, so getting to a vet fast gives the best chance. Never adopt a wait-and-see approach.
The warning signs to act on
If your dog has been near suspect water and shows any of these, treat it as an emergency:
- Vomiting or diarrhoea
- Drooling, or disorientation and stumbling
- Weakness, collapse or seizures
- Difficulty breathing
- Blood in droppings or unusually dark urine
Do not wait for symptoms to worsen. Phone your vet on the way.
How to keep your dog safe around water
This is a hazard you can almost entirely design out of your walks:
- Do not let your dog swim in, paddle in or drink from any water with visible scum, foam or discolouration.
- Take heed of warning signs. Yorkshire Water and local councils post them when blooms are confirmed, so respect the notice even if the water looks fine that day.
- On warm, still spells in late summer and autumn, when blooms are most common, be extra cautious around still fresh water.
- Carry your own water and a bowl so your dog is never tempted to drink from a pond.
- If your dog does get into questionable water, do not let it lick its coat. Rinse it off with clean water as soon as you can and ring your vet.
You can check for local alerts through Yorkshire Water and City of York Council, both of which flag confirmed blooms.
Where this touches grooming
A dog that has been in dubious water needs rinsing promptly, because a bloom trapped in a thick or long coat is a dose waiting to be licked off. This is one reason a manageable, well-maintained coat is safer as well as tidier: it rinses clean far more easily than a dense, matted one. If your dog's coat has got heavy or is holding water and dirt, our salon can help you get on top of it. Ring your vet first if there is any chance of exposure, though. A wash is not a substitute for veterinary attention.
Frequently asked questions
Is blue-green algae really in Yorkshire?
Yes. It has been confirmed on Yorkshire reservoirs such as Grimwith, and City of York Council has issued warnings. It appears most in warm, still weather, typically summer into autumn.
How quickly can it hurt my dog?
Very quickly. Some toxins cause signs within minutes, others within a few hours. Because there is no antidote, speed to the vet is everything.
My dog paddled in water with green scum but seems fine. What should I do?
Do not wait. Rinse your dog with clean water so it cannot lick the algae off, and phone your vet straight away for advice, even if your dog seems well.
Can I tell if a bloom is toxic just by looking?
No. There is no way to tell a toxic bloom from a harmless one by sight, so treat all scum, foam and discoloured water as dangerous.
This isn't veterinary advice
We're professional dog groomers, not vets, so please treat this as friendly general guidance. If you're worried about your dog, or before acting on anything here, speak to your local vet. In an emergency, contact your vet or nearest out-of-hours clinic. For suspected poisoning you can also ring Animal PoisonLine on 01202 509000.
Fluffs is a professional dog grooming salon in Wigginton, York, offering one-to-one grooming for dogs of every breed and coat type across Haxby, Strensall, Huntington, New Earswick and the surrounding villages. A well-kept coat rinses clean far more easily after a muddy or watery walk. Talk to us about keeping your dog's coat in good order.