September 4, 2003

 

Unexplained Livestock Deaths May Be Caused by Cyanobacteria

Drinking stagnant pond water during hot, dry weather can cause death in animals, according to Charles Stoltenow, North Dakota State University veterinarian. "The water can contain certain species of cyanobacteria (formerly known as blue green algae) that typically grows in stagnant warm pond water. One rancher recently lost seven head of cattle because of cyanobacteria."

At least four types of potentially poisonous cyanobacteria occur in North Dakota. Toxins from these bacteria are poisonous to most livestock including cattle, horses, sheep, pigs, chickens, domestic and wild ducks, pigeons, geese and even frogs, fish and snakes.

The toxins primarily affect the nervous system and the liver. Signs of cyanobacterial poisoning include staggering, tremors and severe abdominal pain. The toxins are also poisonous to humans.

Take note of any dead wildlife around bodies of water, Stoltenow advises. A close watch for unexplained livestock deaths is also important. Consult a veterinarian to find a cause of death so steps can be taken to prevent additional livestock deaths. There are no known antidotes for cyanobacteria poisoning.

The algae flourish only in the top few inches of water so toxic concentrations are typically found only in small ponds where waves don’t mix the water thoroughly. Cyanobacteria blooms don’t occur in lakes and rivers. Under favorable conditions, the algae can double in number in 24 hours and can turn pond water blue to brownish green.

If a pond contains toxic concentrations, keep animals from drinking from it by fencing off the water and providing another source of water. Because the toxins are concentrated at the surface, water may be pumped from the bottom of deep sloughs or potholes to watering tanks.

Typically, toxic algae blooms last only a few days but may persist for several weeks. A veterinarian can help determine if a pond has toxic concentrations of the algae.

"If there are continuing problems, producers may want to consider treating the water with copper sulfate or other algicides," Stoltenow says. "Use them only in ponds that don’t drain into other waterways or bodies or water, and don’t consume any plants or fish from the treated pond. Also, because toxin levels increase immediately after treatment, livestock should not be allow to drink from treated ponds for a week. A recommended treatment rate is two pounds of copper sulfate per acre-foot of water. That’s roughly equivalent to eight pounds per million gallons."

More information on cyanobacteria and protecting livestock is available on the Web at http://www.ext.nodak.edu/extpubs/ansci/beef/v1136w.htm

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Source: Charles Stoltenow, (701) 231-7522, charles.stoltenow@ndsu.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu