Pet Owners Should Be Aware of Blue-Green Algae

August 5, 2020

PIERRE, S.D. – As the “dog days” of summer roll on, South Dakota Game, Fish and Parks officials would like to warn pet owners of blue-green algae blooms that are appearing in ponds and lakes across the state.

“Blue-green algae blooms happen every year when summer really gets hot,” said regional fisheries manager, Mark Ermer. “It’s nearly impossible to tell if algae in a pond or lake is poisonous or not, so we recommend not letting dogs swim in a body of water that has a visible, thick layer of algae floating on the surface. Even one drink of water that has a blue-green algae bloom can be fatal for dogs.”

Blue-green algae are most often blue-green in color, but can also be blue, green, reddish-purple, or brown. Blue-green algae generally grow in protected areas of lakes, ponds, and slow-moving streams when the water is warm and enriched with nutrients like phosphorus or nitrogen.

“Blue-green algae blooms are caused by cyanobacteria, which grow particularly well in slow-moving or stagnant water with high phosphorus or nitrogen content,” said South Dakota Assistant State Veterinarian, Mendel Miller. “Some of these cyanobacteria may produce dangerous toxins which, if ingested, can lead to liver or nervous system damage in animals. These toxins cause serious damage quickly, so prompt medical care is critical following potential exposures. Because it is not easy to tell if an algae bloom is producing toxins, it is best to avoid all water where cyanobacteria appear to be present.”

“If you think you or your pet has come into contact with blue-green algae, contact your doctor or veterinarian immediately,“ Miller said. “Symptoms of blue-green algae poisoning include, lethargy, the inability to walk, hypersalivating, weakness, vomiting, diarrhea, pale gums, shock, seizures, loss of appetite, tremors and difficulty breathing.”

Fish consumption from lakes experiencing a high algae bloom should be limited. While the toxins can be present in fish caught during a bloom, research has shown the concentrations of toxins are higher in the organs of fish than in the muscle tissue or fillets. Toxin levels decrease after an algae bloom has ended.

Anyone observing what they believe is a harmful algae bloom should contact their local GFP office or the Department of Energy and Natural Resources.