blue-green algae toxicity in horses

Summertime is known for its heat. Add some rainy days to the mix, and this combination can be the recipe for the development of blue-green algae, says a toxicologist at the Kansas State Veterinary Diagnostic Laboratory, a part of Kansas State University’s College of Veterinary Medicine, in Manhattan.

Also known as cyanobacteria, blue-green algae can bloom in fresh water where environmental conditions—warm weather, lots of sunlight and the presence of nutrients in the water, which often are the result of agricultural runoff—make it possible for these organisms to grow and replicate rapidly.

Steve Ensley, DVM, PhD, a clinical veterinary toxicologist at Kansas State, said health problems can arise when animals—including horses—and people come into contact with the various toxins produced by cyanobacteria.

Horses can develop clinical signs including muscle tremors, respiratory distress, seizures, profuse salivation, diarrhea, liver failure, and rapid death in minutes to hours. If horses survive long enough, treatment is supportive and symptomatic. In some cases animals can recover, but death typically occurs so quickly that the animals are found dead near the water source.

“If there is a bloom in a body of water that animals are drinking out of, then we need to move them away from it as fast as we can,” Ensley said. “Fence off that water source if at all possible.”

If livestock and/or pet owners are worried that their animals could potentially be exposed to blue-green algae, then they should regularly check for signs of its development, Ensley said.

“There is some confusion between the blue-green algae blooms and other vegetation on water,” Ensley said. “If a blue-green algae bloom occurs, then it looks like blue or green paint was spilled on the surface of nonmoving water.”

With warm weather and rainy days on the rise, the risk of blue-green algae blooms persists.

“It’s going to be a concern until we get into cooler weather, so it may be a problem until September as long as the weather stays warm and we continue to get rainfall,” Ensley said. “Rain causes lakes and ponds to become enriched with an excess amount of nutrients, like phosphorus and nitrogen, causing the bacteria to bloom at a more rapid pace.”