What is blue-green algae?

Blue-green algae is a term used to describe a group of bacteria called cyanobacteria. They are not actually algae, but the organisms got this name because they often give the appearance of algae when they clump together in bodies of water.

Blue-green algae can be commonly found in non-flowing water, such as seas (especially estuaries and rock pools), lakes, ponds and rivers. Certain conditions such as hot weather can cause it to thrive and grow rapidly, forming a ‘bloom’ of blue-green algae on the water. It can also be seen during other times of the year.

Some types of blue-green algae contain toxins that can be highly poisonous and often fatal to pets. It can also cause illness in people if touched or swallowed.

What does blue-green algae look like?

Blue-green algae bacteria cannot be seen with the naked eye, unless they clump together. When this happens, or when blue-green algae blooms on the water, it can look like:

• A blue-green scum has appeared on the surface of the water -this sometimes looks a bit like pea soup.
• Green flakes, greenish bundles of brown dots in a pond, lake or stream.
• A green, blue-green or greenish-brown paint on the surface of the water.
• A foam around the edge of ponds and lakes.

You may notice dead wildlife in the sea, ponds or lakes with high concentration of toxic blue-green algae. Do not let your dog drink from any water containing dead animals.

Why is blue-green algae dangerous to dogs?

Dogs are at risk from blue-green algae if they swim in or drink contaminated water, or if they get it caught in their fur and ingest it while cleaning themselves. This is because blooms of blue-green algae can produce harmful toxins which stop a dog’s liver from functioning properly.

Exposure to toxic blue-green algae is often fatal and it can cause long-term health problems in dogs that survive. If your dog shows any of the following signs after drinking from, swimming or paddling in water, contact your vet immediately and tell them you are concerned about blue-green algae:

• Vomiting
• Diarrhoea
• Seizures of fitting
• Weakness or collapsing
• Disorientation
• Drooling
• Breathing difficulties

It’s important to contact your vet immediately as some of these symptoms can be linked with other illnesses.

How to protect your dog from blue-green algae

• Keep them away from bodies of water that you know, or suspect may contain blue-green algae, this includes not letting them swim or paddle.
• Making sure your dog does not drink from water that may contain blue-green algae. The wind can often blow blooms of algae to the edges of bodies of water, which is where dogs are likely to drink.
• During dog walks, take note of any signs that may warn about blue-green algae and follow any information given.

Can blue-green algae affect cats?

Although blue-green algae poisoning is uncommon in cats, as they rarely swim and usually do not like to drink standing water. However, if they do drink contaminated water, it can be fatal, and you should contact your vet right away.