DOG WALKERS WARNED OF DEADLY ALGAE RISK DURING HEATWAVE

Dog owners are being urged to keep their pets away from lakes and rivers this summer due to a surge in toxic blue-green algae blooms.

Officials have reported an unusually high number of these blooms across the UK, driven by recent hot and dry weather.

The blooms occur when certain bacteria thrive in warm, sunny conditions, rapidly multiplying and forming a colorful scum on the water’s surface. If ingested, the toxins can be harmful to humans and deadly to animals—dogs are especially vulnerable.

Authorities and animal welfare experts are advising the public to stay clear of affected rivers and lakes, and to keep children and pets at a safe distance throughout the summer.

Algal blooms have become more common since 2015 because of climate change, experts say.

Charlie Matthias, senior veterinary surgeon at Dogs Trust, told The Telegraph: “With rising temperatures and falling water levels, there’s an increased risk of blue-green algae appearing in lakes and rivers.

“Even in small amounts, blue-green algae can make dogs seriously ill—and in some cases, it can be fatal if ingested.

“We strongly advise owners to keep their dogs from swimming in or drinking from water that appears green, scummy, has surface foam, or is marked with warning signs.

“Because blue-green algae isn’t always visible, it’s safest to avoid letting your dog near the water if there’s any doubt.”

These harmful blooms occur when warm weather and nutrient-rich water—often contaminated by agricultural runoff—trigger the rapid growth of cyanobacteria. Still or slow-moving bodies of water are particularly vulnerable.

Once established, blooms can linger for months, lasting until colder weather returns. Authorities expect the risk to remain high throughout the summer.

The UK Centre for Ecology and Hydrology (UKCEH) runs a “Bloomin’ Algae” project where the public send in images of suspected toxic blooms and experts determine if it is.

Data show that half of the about 200 submissions this year are blue-green algal blooms, with a further 34 being “plausible”.

The blooms have been found across the UK from Norfolk and Essex to Birmingham and the Lake District and submissions show that some dogs have fallen ill for several days after going for a swim.

Confirmed cases have also been reported by people swimming or paddle-boarding in affected waters. Once a bloom is identified, landowners are required to display warning signs to alert the public.

In dogs, symptoms of blue-green algae poisoning can appear within minutes and may include vomiting, diarrhea, excessive drooling, muscle tremors, seizures, difficulty breathing, and collapse.

Immediate veterinary attention is critical, as there is no known antidote. The toxins target the liver and nervous system and can be fatal. However, if caught early, a vet may be able to flush the toxins from the dog’s system and improve the chances of recovery.

Dr. Linda May, a freshwater ecologist at the UK Centre for Ecology and Hydrology, explained: “Dogs are especially vulnerable because they are sensitive to the toxins some algal blooms release into the water.

“Even small amounts can be deadly for smaller dogs, so if your dog shows signs of illness after being in contaminated water, please seek veterinary care immediately.”

Anna Ewers Clark, veterinary standards lead at the national pet charity Blue Cross, added: “While there is no specific antidote, supportive treatment is vital. These toxins are extremely dangerous and can be fatal, even with medical intervention.

“This is very worrying—just a small amount of contaminated water, or even licking it off their fur, can be harmful.”

An Environment Agency spokesperson said: “Blue-green algae is a natural environmental occurrence that thrives during warm, dry, and calm weather, posing risks to both animals and humans.

“We encourage anyone who suspects a blue-green algae bloom in rivers, streams, or lakes to contact our 24/7 incident hotline at 0800 80 70 60. Our teams will collect and test samples to ensure appropriate warnings are issued.”