Blue-green algae produce toxins that are hazardous to humans and can be fatal in animals, particularly dogs, said Deon van der Merwe, associate professor of diagnostic medicine and pathobiology. Blue-green algae, also known as cyanobacteria, grow in bodies of water, such as lakes and ponds, and other wet places, such as moist soil or rocks.
“Essentially anywhere there is water, you can find blue-green algae,” said van der Merwe, who also manages the toxicology section of the Kansas State Veterinary Diagnostic Laboratory.
Blue-green algae develop when water has excess nutrients, which helps cyanobacteria grow rapidly and creates an algae bloom. Discolored water or algal scum can be signs of an algae bloom, which can last anywhere from a few days to several weeks. Cyanobacteria need sunlight to grow because they are photosynthesizing organisms, van der Merwe said.
“If there is a lot of sunshine and if the weather is warm, that makes it easier for them to grow rapidly,” van der Merwe said. “That’s why blooms occur most frequently in the summer, especially in drought conditions. Under drought conditions, you typically have many cloudless days and more sunlight reaching water.”
Health problems can arise when animals and people come into contact with the various toxins produced by cyanobacteria. The most prominent problem involves a toxin called microsystin, which affects the gastrointestinal tract and liver, van der Merwe said. When animals are exposed to this toxin, they may experience vomiting or diarrhea. If the cyanobacteria exposure is severe, it can be lethal and cause liver failure in animals.
Although gastrointestinal problems and liver failure also are possible in humans after blue-green algae exposure, irritant effects are more common. Humans often experience skin rashes, sneezing, coughing, irritated eyes, running noses and conjunctivitis after blue-green algae exposure.
“If you go to a lake or pond and the water is green, it is important to avoid physical contact with that water,” van der Merwe said. “If people swim or ski behind a boat and they inhale spray from behind that boat, those can also be situations in which people can be exposed.”
Although blue-green algae affect all animals, they primarily affect dogs because of their behaviors, van der Merwe said. Dogs often roam around and seek out algal scums in the water or on the lakeshore. This is dangerous because even when the scum has dried, it still can maintain toxicity.
“If people suspect that their dog has been exposed and the dog starts to vomit, that is often the first sign you will see,” van der Merwe said. “It is very important to get the dog to the veterinarian as soon as possible. It may be possible to do preventative treatment to stop the full development of the poisoning.”
It’s also important for pet owners to protect themselves from blue-green algae exposure, van der Merwe said. Pet owners should wear protective gloves when handling animals that have been exposed to blue-green algae.
“It is a risk for people as much as it is for animals,” van der Merwe said.
Blue-green algae can affect other animals — such as birds, deer, cattle, horses and other livestock — that use open water. Cyanobacteria blooms can even cause massive fish die-offs, van der Merwe said. As the algae bloom goes through its normal cycle of blooming and dying, the millions of decomposing organisms reduce the levels of oxygen in the water, which can kill fish.
The Kansas State Veterinary Diagnostic Laboratory accepts water samples to test for blue-green algae. Samples can be dropped by the laboratory from 8 a.m. to 5 p.m. weekdays or shipped to the laboratory in an insulated box with a cold pack. The address for the Kansas State Veterinary Diagnostic Laboratory is 1800 Denison Ave., Manhattan, KS 66506. For more information, contact the laboratory at 866-512-5650 or visit www.ksvdl.org.