Toxic algae bloom poisons dog

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The algae, also known as cyanobacteria, may affect the nervous system or livers of animals.

A dog hovered near death Wednesday battling liver failure after contact with water in Middle Foy’s Lake probably contaminated with blue-green algae, according to the Flathead City-County Health Department.

Kalispell veterinarian Dr. Kelly Rankin alerted the health department to the problem after she treated a dog exposed a few days ago to what appears to be a deadly toxin.

She said the very small Australian shepherd initially responded to treatment but since has shown signs of deterioration from liver failure.

Rankin, who practices at Flathead Animal Clinic, said this dog most likely got poisoned from licking the algae off its coat rather than from drinking a large amount of contaminated water.

“If there is a large ingestion, animals have been known to die in three to five minutes,” she said. “It’s very rare for them to survive.”

Rankin said she had another case on Sept. 29, 2008, when a dog from the same area was brought in too late for any treatment.

Rankin said the same conditions apparently have allowed the algae to bloom again in the stagnant water of Middle Foy’s Lake.

Middle Foy’s Lake is the one set back from Foy’s Lake Road, just below the larger Foy’s Lake with its popular public docks and beaches.

Flathead County Health Officer Joe Russell said Wednesday that he has fielded calls from people asking about the safety of the main Foy’s Lake.

“It may be that there are parts of Upper Foy’s Lake that I might be concerned about,” Russell said. “Any time you see something scummy on the surface, I would be concerned.”

He said the deep water would not be a problem but shallow areas not disturbed by wind might grow blue-green algae. This scum on the surface of the water may take on a paint-like appearance in a variety of colors, not just blue-green.

Blue-green algae (also called cyanobacteria) occur naturally in water bodies and only become a problem with prolific growth called algal blooms. 

Warm, shallow undisturbed water receiving plentiful sunlight creates optimal conditions for blue-green algae growth that forms rafts or scum on the water’s surface.

Some blue-green algae species produce toxins that may affect the nervous system or the liver. Health officials warn  that pets and livestock should not be allowed in water that historically has had problems with blue-green algal blooms or if rafts or scum are visible. 

“There could be immediate death,” Russell said. “This toxin is pretty severe.”

Human exposure without consumption of contaminated water may cause irritation of the skin, eyes, nose and throat and in some instances cause respiratory problems.

Russell said most people don’t drink the water when recreating in a lake, adding that this is another reason they should not.

He urged people to use common sense and keep themselves and their animals out of any water with a scum or film that makes it appear unclean.

Rankin e-mailed information from a university extension service that said nearly all animals — cattle, sheep, horses, pigs, dogs, ducks, fish and wild animals — can be poisoned. Toxins affect the liver or the nervous system with different symptoms.

Livestock affected by nervous system toxins may have muscle tremors, decreased movement and difficulty breathing. They may collapse and go into convulsions or show no symptoms before collapsing and dying.

Animals impacted by liver toxins show weakness, pale mucous membranes, mental derangement, bloody diarrhea and finally death.

People with questions may contact the Flathead City-County Health Department at 751-8101.

Reporter Candace Chase may be reached at 758-4436 or by e-mail at


A mat of blue-green algae covers the surface at the edge of Middle Foy’s Lake. The algae can produce a toxin that is lethal to animals.

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