DOG owners are being warned against letting pets swim in lakes and ponds after deaths due to toxic blue-green algae blooms.

Known as cyanobacteria, blue-green algae occurs naturally in inland waters, estuaries and the sea - and it can be toxic to both humans and animals.

The infection has spread across the UK's lakes and ponds this summer and claimed the lives of four dogs in Sussex, Cheshire, Edinburgh and Northern Ireland.

As a result, the British Veterinary Association has put out a warning, which says: "An increase in reports of toxic blue green algae in several locations across Wales and other parts of the UK this summer is prompting the BVA to urge pet owners to take extra precautions while walking their dogs."

In early June, a dog died from suspected exposure to deadly algae near Horsham.

The dog was swimming in Wephurst Wood near Loxwood in the Chichester district recently when it was thought to have come into contact with the deadly algae.

After the swim, the dog fell ill and was taken to Arun Veterinary Group's out-of-hours hospital in Storrington by South Downs Emergency Vets. It was put down after being unconscious and seizuring for six hours.

Similar incidents occurred elsewhere in the UK last month.

A King Charles Cavalier named Kendall reportedly fell ill within minutes of paddling in a lake which was contaminated with toxic blue-green algae in Hatchmere Lake, Cheshire.

Symptoms of blue-green algae poisoning

If a dog shows any of the following signs after drinking from, or swimming or paddling in water, you should visit your vet immediately:

  • Vomiting/being sick
  • Diarrhoea Seizures/fitting
  • Weakness/collapse/unconsciousness
  • Disorientation/confusion
  • Drooling
  • Breathing difficulties

How to spot blue-green algae in water

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

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, according to the Blue Cross.

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

Blooms of the organisms often build up around the edges of ponds and lakes, which may look like foam.

It is most common in non-flowing fresh water such as lakes and ponds during hot weather when there is less rainfall, but can also occur at other times of the year.

You may notice dead fish in ponds or lakes with a high concentration of the toxic bacteria. Don’t let your dog drink from water containing dead animals.

The algae may be present in a harmful form even if you cannot see it, so take note of any warning signs in the area.

According to the Environment Agency, not all blue-green algae blooms and scums are toxic, but you can’t tell just by looking at them, so it’s best to assume they are.

Often times, once algal numbers reach high levels, the bloom will last for an entire season, declining only on the onset of winter conditions.

Anyone who sees a body of water they believe may be affected by the algae is advised to contact the Environment Agency incident line on 0800 80 70 60.