Blue-green Algae (Cyanobacteria)

Photo credit: The image was not adapted or changed.
Photo credit: The image was not adapted or changed.

As temperatures climb during the summer months, conditions can become ripe in waterways to produce toxic blue-green algae – or cyanobacterial – blooms that can be deadly to pets, with animals often dying within 15-20 minutes after exposure.

Animals can be exposed to blue-green algae and its toxins by simply contacting any affected water body, including ponds, lakes, streams, rivers, or even residential decorative ponds and neglected swimming pools.

What are blue-green algae?

Cyanobacteria, also referred to as blue-green algae, are microscopic organisms that live in fresh bodies of water that usually multiply and bloom when water is warm, stagnant, and rich in nutrients like phosphorus and nitrogen from sources such as fertilizer runoff.

The toxins that cyanobacteria produce come in four types and can be very deadly. The toxins can specifically affect the liver, the kidneys and liver together, the nervous system, or the skin.

How do I know if water is contaminated with blue-green algae?

It is impossible to tell whether a given body of water has a toxic bloom currently without sophisticated testing. During warmer months, it is best to assume all surface waters are potentially contaminated.

Sometimes, blooms will present as thick, gooey, green slime on and in surface waters and eddies of running waters. Blooms can also be red or brown.

Often, concentrations will occur in just one part of a waterway.

Dead fish, waterfowl, or other animals around a water source may indicate the presence of blue-green algae.

What are the symptoms for an animal exposed to blue-green algae?

Signs of poisoning usually occur within 15-20 minutes after ingestion. Symptoms can include:

  • Skin rashes
  • Vomiting
  • Diarrhea
  • Blood in stool or black, tarry stool
  • Weakness
  • Pale mucous membranes
  • Jaundice
  • Seizures
  • Disorientation
  • Coma
  • Shock
  • Difficulty breathing

What should I do if I think my pet may have been exposed?

Immediately contact your vet or the WSU Veterinary Teaching Hospital at 509-335-0711.

The time from exposure to death can be mere minutes to hours without aggressive and experienced veterinary intervention.

How can I protect my pet from blue-green algae?

To reduce the chance of your pet being exposed to blue-green algae:

  • A good rule of thumb for you and your pet is: When in Doubt, Stay Out!
  • Don’t let animals swim or drink where there is noticeable algae in the water or scum on the shore.
  • If pets swam in water that could have harmful algae, rinse them off with fresh water immediately. Don’t let them lick their fur.
  • If your pet experiences any symptoms after exposure to algae, contact your veterinarian immediately.

This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.