OREGON STATE UNIVERSITY

Naturally occurring toxin cause of death in Oregon dog

09/10/2009

CORVALLIS, Ore. – A dog that died suddenly after being in the water near Elk Creek in southern Oregon late last month has tested positive for anatoxin-a, a neurotoxin released by naturally occurring blue-green algae, Oregon State University technicians have confirmed.

The dog was tested at OSU’s Veterinary Diagnostic Laboratory, which confirmed the cause of death. At least two other dogs in the same area have died recently under similar circumstances, presumably from the same cause.

“Blue-green algae, or Cyanobacteria, produce toxins that can result in illness and death,” said OSU’s Jerry Heidel, director of the state’s only accredited veterinary diagnostic lab. “A ‘bloom’ or rapid increase in the growth of these algae results in a large number of these organisms in the water. Algae ingested with this water are rapidly broken down in the stomach and potent toxins are released, which can be fatal.”

Heidel said anatoxin-a is a strong neurotoxin that causes almost immediate clinical signs, including muscle tremors, respiratory disease and convulsions. Respiratory paralysis can lead to death within 20 to 30 minutes, he added.

“Once ingested, there isn’t a lot a person can do,” Heidel said. “Diluting the toxins by drinking clean water probably won’t even help. Immediate treatment by a veterinarian is essential, but the prognosis once clinical signs begin is poor. The real key is prevention – and that can be difficult to do.”

Heidel said these naturally occurring neurotoxins also can harm humans, which is why some Oregon lakes have closed in recent years during algal blooms. Livestock also are susceptible to anatoxin-a, and several cows die each year after ingesting stagnant pond water.

Heidel said algal blooms occur in standing, or slow-moving water, during warm temperatures – usually in summer – when there is a good nutrient source to promote growth. Winds can concentrate the algae along shorelines, he added, increasing opportunities for people and animals to contact and ingest the organisms.

“Oregon agencies monitor popular bodies of water frequented by the public for the presence of algae blooms and do a good job of issuing alerts when those waters are potentially dangerous,” Heidel pointed out. “But the public needs to be aware that these potentially fatal blooms can occur in any body of standing or slow-moving water.

“If you take your dog for a walk in the woods, or along a drying creek or lake bed, watch for stagnant, often cloudy water that appears to have algal growth,” he added.

OSU’s Veterinary Diagnostic Laboratory provides the state with a range of animal disease diagnostic services to veterinarians, livestock producers, pet owners, biomedical researchers, and state and federal agencies. More than 16,000 animal tissue and fluid specimens are received annually by the laboratory for diagnostic evaluation. The laboratory also provides a variety of diagnostic procedures, including necropsy, histopathology, virology, bacteriology, clinical pathology, serology and toxicology.