The following overview of blue green algae poisoning in livestock was written by Rachel Endecott (Former MSU Extension Beef Cattle Specialist).
Blue-green algae (cyanobacteria) are photosynthetic bacteria that live and grow in aquatic environments. Many species exist: some species are harmless, while others can affect the nervous system and liver function of livestock. Large blooms of cyanobacteria can occur when conditions are favorable, leading to elevated concentrations in water sources. When livestock or other animals ingest high concentrations of blue-green algae, death can occur within minutes or hours.
Poisoning usually does not occur unless there is a heavy bloom that forms a dense surface of scum. Colonies may look like a skin or paint on or just below the water surface. Contributing factors to heavy blooms include nutrient-rich water (nitrogen and phosphorus, for example) and warm, sunny weather. Even a light wind can lead to very high (scum) concentrations of blue-green algae, especially downwind shoreline locations where livestock drink.
Ruminants (cattle and sheep) and birds are more sensitive to toxins than monogastrics. Among domestic animals, dogs are most susceptible. Ranchers have reported dead birds and other wildlife along shorelines of affected water sources. Signs of blue-green algae poisoning would include tremors and difficult breathing if affected by the neurotoxin. At high doses, the neurotoxic effects can take place within minutes. Often, ranchers report sudden collapse and death immediately after consumption of the affected water. Hepatotoxic effects would take longer (hours rather than minutes) after toxic water consumption to be observed.
Water samples can be evaluated at a lab for the presence of toxic cyanobacteria and for analysis of cyanotoxin level.
For further information on algae poisoning or livestock management, please contact the Chouteau County Extension Office at 622-3751 or stop in for a visit. We are located in the green building next to the courthouse.
Montana State University U.S. Department of Agriculture and Montana Counties Cooperating. MSU Extension is an equal opportunity/affirmative action provider of educational outreach.
