Beware of Toxic Pond Scum, aka Blue-Green Algae

[blue green algae]In recent weeks you might have heard talk of “blue-green algae.” According to the ASPCA Pet Poison Center, there has been a spike in reported cases. A number of Facebook stories have also attributed the death of dogs across the United States to this toxic “algae.” The social media interest has prompted many major news stations to air segments about this “algae.”

Here is a brief overview of this toxin and pointers to help keep you and your pets safe.

Blue-green algae is actually not even algae but a naturally occurring bacteria known as cyanobacteria. During rapid growth phases, this bacterium produces colonies that create “blooms.” These bacterial blooms create a blueish-green paint-like look to the surface of the water. The look of the bacteria resembles algae, hence the name blue-green algae.

Cyanobacteria can be found in all fresh water lakes, streams, and ponds and is most prevalent in the warmer summer months. The bacteria may produce toxins that can cause illness, but not all cyanobacteria produce these toxins.

To be safe, it is best to avoid all water sources that appear to have any presence of blue-green algae (blue-green paint-like appearance, surface mats, discolored green/blue streaks). The State of Illinois recently issued a warning to Illinois residents about the potential of blue-green algae and recommends to avoid contact with suspicious-looking water.

For those of you who live in Chicago, the Chicago Park District issued a warning in June recommending staying away from the Humboldt Park lagoon, where traces of blue-green algae had been detected. The Park District posted big yellow signs around the lagoon warning visitors of the potential risk. Look for the yellow warning signs around Chicago parks, but if the water looks suspicious, do not let you dogs in the water or allow them to drink the water.

There are various toxins that can be produced by cyanobacteria. Mild forms of illness include lethargy, vomiting, diarrhea, and weakness. More severe toxins affect the neurologic system and can lead to death within 15 minutes of exposure.

Given the toxicity of this dangerous bacterial toxin, it is safest to avoid bodies of water where there is the potential of blue green algae. If you have any questions about blue-green algae, please don’t hesitate to contact your veterinarian.

Drew Sullivan, DVM
Medical District Veterinary Clinic


Sources and for more information, visit these sites:

ASPCA Pet Safety Alert:

State of Illinois Warning:

Pet Poison Hotline Blue-Green Algae:

Chicago Tribune warning:

Featured image from Wikimedia Commons.