Blue-Green Algae: Pet Alert


Blue-green algae occurs naturally in bodies of freshwater, but some kinds can be toxic to humans and lethal to animals. 

It is impossible to tell by looking if the algae are the dangerous kind just, so it is advisable to not enter or allow you pets to enter the water if you suspect the presence of blue-green algae.

Vets are urging dog owners to be extra careful when walking their pets near rivers or lakes this summer as the hot weather has prompted concerns about an increase in toxic blue-green algae.

Blue green algae, or cyanobacteria, are a group of bacteria that can contain dangerous toxins which are be harmful and potentially fatal to pets, livestock, and birds if ingested.

Symptoms commonly include vomiting, diarrhoea, trouble breathing, seizures, and blood in faeces. Left untreated the toxins can cause liver damage and death.

Blue-green algae cannot actually be seen until they start clumping together. Once they clump, there are a few different ways blue-green algae appear in water:

  • They can look like a green or blueish scum on the water
  • It might look like someone has thrown blue or green paint into the water
  • They might clump together to look like seaweed
  • They can appear in brown clumps alongside other weeds in the water
  • They can appear as green flakes or brown dots
  • They can turn water cloudy and give it a green, blue-green, or greenish-brown appearance
  • You might see foaming on the edge of the shore, which can look like sewage pollution.

Better to be Safe than Sorry

Some, but not all, blue-green algae species release dangerous toxins into the water. There is no way of telling if algae are toxic just by looking at the water and even blue-green algae are not always toxic – some types are safe while others are only toxic at certain times of year when they are blooming. If you are worried there may be blue-green algae, it is best to keep your dog far away from the water. Do not let your pets touch or drink from the water.

Sometimes if blue-green algae are present, you might notice dead fish or other wildlife in the water. Never let your dog drink from water with dead fish in it.

A paddle in a cool lake may be your dog’s favourite outdoor activity at this time of the year, but pet owners are urged to keep their dogs on a lead during walks near water bodies confirmed to have algal blooms.