The British Veterinary Association (BVA) is warning owners to keep their dogs out of lakes, ponds, reservoirs, and other waterways after blooms of toxic blue-green algae have appeared across the UK. The warning comes after several reports of dogs becoming ill or even dying after swimming in water suspected to be contaminated with the blue-green algae—which produce one of the most potent biological toxins in the natural world. As there is no known antidote for the toxins, it presents a serious threat to pets and humans alike. Here’s everything you need to know about the deadly organism.

What are blue-green algae?

Different types of algae occur naturally in most aquatic ecosystems such as ponds, lakes, canals, rivers, and streams, and during long periods of warm weather with minimal rain they can multiply rapidly, forming what are known as blooms. But while blue-green algae contain chlorophyll (the green pigment used in photosynthesis) they are not technically plants—they are organisms that date back billions of years, called cyanobacteria. In fact, the World Health Organization classifies them as bacteria, not a type of plant:

“Cyanobacteria are also known as blue-green algae, so named because these organisms have characteristics of both algae and bacteria, although they are now classified as bacteria. The blue-green colour comes from their ability to photosynthesize, like plants.” (source)

When the bacteria decay, toxins that can severely harm humans and can kill wild animals, livestock, and pets are released, occasionally alongside a turquoise pigment and a potent odour similar to rotting vegetables.

What does a toxic algae bloom look like?

Cyanobacteria blooms may appear as green, blue-green or even greenish-brown scum on the water’s surface. They can look wispy, foamy, lumpy, paint-like or make the water appear cloudy. They’re also frequently confused with duckweed and blanketweed (filamentous algae)—both of which are harmless.

The BVA’s junior vice president Danielle Dos Santos warns: 

“While not all blue-green algae are poisonous, it is impossible to tell the difference visually, so it is better to be safe than sorry.”

To this end Prof Laurence Carvalho of the UK’s Centre for Ecology and Hydrology and his team developed an app called ‘Bloomin’ Algae’ which helps people to identify blue-green algae and record where it’s been spotted. The general public are encouraged to upload photos of algae they suspect to be toxic and the team of experts will do their best to determine if it is in fact dangerous—helping to speed up public health warnings. You can download the app directly from Google Play or App Store.

Find more about the app from Prof Laurence Carvalho here:

How are pets exposed to toxic algae?

In addition to swallowing algae by drinking water from an affected lake, canal, pond or river, dogs can also easily ingest it when swimming, playing in water or when licking their fur after going for a swim. 

The RSPCA advises owners to err on the side of caution: 

“We’d urge dog walkers and owners to keep their pets away from any body of water that you suspect may contain blue-green algae. Don’t let them paddle or swim in the water and don’t let them drink from it.”

Is blue-green algae present in my area?

Several locations across the UK have been affected by toxic algae blooms this summer, prompting the British Veterinary Association’s cautionary warning. The national body for vets said that the presence of cyanobacteria has been confirmed in bodies of water in Southampton and Fleet in Hampshire, Edinburgh and Elgin in Scotland, Cornwall, Leicestershire, Derbyshire, and Lincolnshire, so far this summer. It has been reported that at least four dogs have died in the UK after coming into contact with water known or thought to have been contaminated. 

Use the ‘Bloomin’ Algae’ Citizen Science app to see if any toxic algae blooms have been reported in your area or to raise the alarm if you spot one.

How dangerous is blue-green algae?

Blue-green algae is extremely harmful to animals, so even ingesting a tiny amount is enough to be fatal. Cyanobacteria produce toxins that can cause damage to the liver and nervous system, and there is presently no cure, as the British Veterinary Association’s Danielle Dos Santos explains: 

“There is currently no known antidote for the toxins, so prompt veterinary treatment is essential to tackle their effects and ensure a good chance of recovery. If you suspect your dog has been exposed to blue-green algae, rush it to your local vet without delay.” (source)

Though instances of poisoning in humans are rare, Prof Carvalho of the UK’s Centre for Ecology and Hydrology says that a number of studies in the US had examined whether there was a link between cyanobacteria blooms and clusters of motor neurone disease and Alzheimer’s cases close to lakes. (source)

What are the symptoms of blue-green algae poisoning in dogs?

Depending on the type of toxin ingested, symptoms from exposure to toxic algae can appear within a few minutes or hours. If your dog is experiencing any of these signs and you suspect they’ve come into contact with contaminated water you should take them to the vet immediately. If left untreated, dogs can incur liver damage and die very quickly.

• Vomiting
• Diarrhoea
• Excessive drooling
• Disorientation
• Difficulty breathing
• Collapsing
• Seizures
• Blood in faeces

How can I prevent my dog from being exposed to toxic algae?

British Veterinary Association’s junior vice president Danielle Dos Santos says: 

“We know that some dogs enjoy nothing better than a paddle in a cool lake while on a walk during summer months, but my advice to pet owners would be to keep your dog on a lead during walks near water confirmed to have toxic algal blooms.”

The BVA issued these further tips to keep dogs safe:

• Look out for warning signs put up by the Environment Agency or councils near water bodies.
• Keep pets on a lead and by your side around water bodies known or suspected to have blue-green algal blooms.
• If your dog has been swimming outside, wash them thoroughly with clean water afterwards.
• Rush your pet to a vet immediately if you believe they may have ingested toxic algae.

The bottom line

Prevention is key so heed the experts’ warnings and steer clear of water that may have been contaminated. If you’re unsure, do not let your dog go near the water and use the ‘Bloomin’ Algae’ app to send a photo of the bloom to their team of freshwater ecologists for examination. And if you suspect that your dog could be contaminated head to the vet immediately. 

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Featured image: Sheila Sund/Flickr