Haywards Heath: 01444 456886

Rottingdean: 01273 359090

Peacehaven: 01273 359092

01444 456886

01273 359090

01273 359092

Are algae dangerous to my pets?

Dog owners do need to be careful of blue-green algae.

Whilst some are harmless, others do produce a variety of toxins that may cause a range of problems to animals that drink water containing the algae. Occasionally these toxins can be fatal.

Possibly the worst-case scenario is a dog that swims and plays in a pool with blue-green algae, drinking as they go, and then grooms itself clean afterwards, causing an additional amount of toxin to be swallowed directly from the fur.

A variety of problems might occur, depending on the species of blue green algae. These usually range from gastrointestinal upsets like vomiting and diarrhoea, to liver damage or neurological problems such as seizures.

Blue-green algae are not actually algae, but the organisms were given this name because they often give the appearance of algae when they clump together in bodies of water.

They are most commonly found in non-flowing fresh water such as lakes and ponds during hot weather, but can also occur at other times of the year.

The bacteria cannot be seen with the naked eye unless they clump together. When this happens, blue-green algae can look like green flakes, greenish bundles or brown dots in a pond, lake or stream.

When the algae blooms, it can look like a blue-green scum has appeared on the surface of the water.

The Environment Agency had to close their testing service and laboratories last year, but testing has restarted this summer.

If you suspect a stagnant pool or pond near you might be affected, there is an app called the Bloomin’ Algae app for reporting your concerns. You upload a photo, and the app will quickly identify whether or not your concerns are well founded.

The app also manages a map of ponds checked, so you can see whether or not to allow your dog to chill out in the water.

Should your dog swim, remove them as quickly as you can, prevent them from drinking the water or grooming themselves, and give them a good shampoo as quickly as you can. If they then show any worrying symptoms, report to a vet immediately. But also remember to snap a quick shot of the pond for the app, so that other dog owners can be warned too.

Latest News from the Mewes

Endocrinopathies were a mystery
At vet school we studied many topics, but one that baffled me was Endocrinopathy.   Perhaps it was because I had never heard of the...
Mewes News
Thu 5 March 2026
Student lessons in stress management
Years ago, as a student vet seeing practice at a mixed vets in Watford, I was asked to help. One of the large animal vets...
Mewes Memories
Thu 19 February 2026
New tooth brushing service for dogs
I’ve always been as interested in preventing illness as I am in curing it. For years I have been encouraging as many puppy and kitten...
Haywards Heath
Thu 12 February 2026

🚨 Emergencies

During practice opening hours, please call your local practice.

Haywards Heath: 01444 456886
Rottingdean: 01273 359090
Peacehaven: 01273 359092

Should your pet require urgent medical care outside of practice hours, please call our emergency referral service, PETS, on 01273 566993.

PETS location: The Deneway, London Road, Brighton, BN1 8QR