Blue-green algae are a type of bacteria called cyanobacteria, which produce toxins called cyanotoxins. Exposure to water that contains these toxins is dangerous and potentially deadly to several species, including humans and their pets.
Blue-green algae live in non-running, freshwater ecosystems such as lakes and ponds, and grow in colonies called “blooms” that give water a blue-green appearance. Colonies of toxic blue-green algae are sometimes called harmful algal blooms (HABs). Not all blue-green algae are toxic blue-green algae; however, because the only way to determine the safety of algae is to test it, the Pet Poison Helpline recommends considering all algae blooms as potentially dangerous.
Where Blue-Green Algae Occurs
Blue-green algae are present throughout North America. According to the American Society for the Prevention of Cruelty to Animals (ASPCA), these blooms “thrive in bodies of fresh water when the weather is warm (over 75 degrees) and sunny.” Lynn Buzhardt, DVM elaborates that algae “grow readily in hot, humid climates where water is warm. Although the largest algae bloom occurs in late summer and early fall, it has a longer growing season in temperate climates.”
Animals Are Affected by Toxic Blue-Green Algae
As Miranda Carney writes in an article for the American Kennel Club, dogs are generally viewed as being at higher risk because they are more likely to play in or drink from non-flowing freshwater. However, other animals including pasture animals (for example, cows, horses, or sheep) are also at risk: “Livestock that drink stagnant water from troughs may also ingest toxic algae,” says Dr. Buzhardt. She also notes that, while cats are also susceptible to cyanobacteria, they are at lower risk because “they rarely swim and are pretty picky about the water they drink.”
Symptoms of Toxic Exposure to Cyanobacteria
As Kendall Curley explains in the article How to Protect Your Pet from Toxic Blue-Green Algae, several cyanobacteria produce toxins that “affect different parts of the body.” Symptoms of exposure vary according to the particular type of toxin: