Lake Southampton

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Marie Keates


An outbreak of blue-green algae led to the closure of a boat lake in Southampton

Dog owners have been warned to take extra precautions when they are walking their animals, while more and more cases of potentially toxic blue-green algae have been reported.

The British Veterinary Association (BVA) has reported an increase in the number of reported cases, including Southampton, Edinburgh, Cornwall and Lincolnshire.

Contact with algae can be fatal for animals if it is not treated and can cause rashes and diseases in humans.

The BVA urged the owners to keep the dogs leashed around the affected water.

The result is a number of cases of dogs that have fallen ill or even died after swimming in water suspected of being contaminated with blue-green algae.

In July, a King Charles Cavalier reportedly died after swimming in a lake in Delamere Forest, Cheshire, which was subsequently closed due to the presence of blue-green algae.

  • Pleasure Lake closed after the discovery of blue-green algae
  • Why blue-green algae is a problem for your pet

Algae are naturally present in inland waters such as rivers, streams and lakes and can multiply during long periods of warm weather and form flowers.

Blue-green algae or cyanobacteria – a type of flowering algae – can produce toxins that are harmful to humans and animals.

These toxins can be dangerous for animals if they are ingested, even in small quantities, said the BVA.

Dogs can swallow algae by drinking water from a lake, from a river or from an affected pond, or by licking the fur after a swim, the release adds.

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According to the BVA, symptoms can appear in minutes or hours, depending on the type of toxins ingested, and usually include:

  • vomiting
  • diarrhea
  • drool
  • disorientation
  • difficulty breathing
  • seizures
  • blood in feces

If left untreated in animals, toxins can cause liver damage and ultimately be fatal, BVA said.

In humans, contact with the skin or ingestion of contaminated water can cause rashes, vomiting, abdominal pain, fever and headache. In rare cases, algae can cause liver and brain damage.

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Algae blooms can be green, blue-green or greenish-brown and can produce musty, earthy or grassy odors.

It is not possible to determine if a proliferation of algae is toxic by looking at it. The Environment Agency says that it is safer to assume that this is the case.

It is advisable to keep pets and children away from the affected water and to avoid any contact with the skin.

According to public health advice, people who come in contact with water containing blue-green algae should shower immediately with fresh water and consult a doctor if they become ill.

BVA Deputy Vice President Daniella Dos Santos said that there is currently no known antidote for toxins and that prompt veterinary treatment is essential to ensure good chances of cure.

"If you think your dog has been exposed to blue-green algae, send it to your local veterinarian immediately," she added.

Daniel Start, author of Wild Swimming, recommends that users search for blue-green algae before traveling to rivers and lakes, especially on the leeward side of lakes where they tend to accumulate.

He added that if algae were present, people should find another place to swim, as rivers are generally less likely to be affected.

How to keep your dog safe

  • Watch for warning signs installed by the Environment Agency or local councils near the water
  • Keep dogs on a leash and by your side around known or suspected water to have a bloom of blue-green algae – do not let them swim or drink.
  • If your dog swam out, wash it thoroughly with clear water then
  • Take your pet to a veterinarian immediately if you are concerned that he has ingested toxic algae

Source: British Veterinary Association