Experts urge caution after three dogs die from blue-green algae poisoning

Updated: August 27, 2019

On Tuesday, CBS News reported that three dogs died after swimming in a pond filled with blue-green algae in Wilmington, North Carolina. The dogs experienced seizures soon after coming into contact with the algae and were rushed to a local veterinarian. All three dogs were put down later that night.

The eponymous blue and green (sometimes brown) algae floats along the surface of waterbodies in sludge-like clumps or long, stringy clusters. At times, it also lines the bottom of waterbodies like a mat, and is naturally found in areas like lakes, rivers, ponds, and streams.

“It’s a cyanobacteria,” says Stephanie Merrill, a board member of the Nashwhaak Watershed Association in New Brunswick, and it can prove poisonous, especially to dogs.

Blue-green algae only poses a threat if the contaminated water is ingested. No human deaths have ever been attributed to ingesting water containing cyanobacterial toxins, but it can cause nausea, headaches, vomiting, diarrhea, fever, and abdominal pain. If you have ingested any contaminated water, Merrill suggests calling your local health department for treatment.

Dogs, however, are a different story. “They like to get in there and swim and gulp and cool off,” Merrill says, making them much more likely to ingest large quantities of contaminated water. If you do notice that your dog has been drinking contaminated water, Merrill says, “You would certainly want to contact a veterinarian to assess the situation.”

The Wilmington incident is not the first case of dogs dying from blue-green algae poisoning this year. Merrill says that a number of dogs have died recently from the same type of poisoning in New Brunswick’s Saint John River system.

These incidents are becoming more common, Merrill says, as climate change’s warming effects exacerbates the spread of blue-green algae. “[We’re] seeing more and more of this popping up across the country, especially on the east coast,” she says. “We’ve seen blue-green algae be persistent for longer periods of time, but [the quantity] is kind of a new thing that’s spreading across the maritime provinces.”

Blue-green algae blooms occur in stagnant water during waves of warm weather, particularly peak summer months like July and August “when the water is getting much warmer and the days are hot.” Flowing water, however, tends to agitate the algae, cooling the water and preventing any blooms from taking root.

But once the blooms are established, they grow like plants, gaining energy through photosynthesis and the input of nutrients like phosphorous into the waterbody.

To protect yourself and your pets from blue-green algae poisoning, Merrill says it’s important to try and “get to know what types of algae outbreaks and their characteristics are typical to a particular lake or river system near you, so that you are able to identify the risk when it is in bloom.”

Often there are local organizations that disseminate the risks of blue-green algae to the public. Otherwise, if you’re looking for more information, check your local health department’s website for advisories on blue-green algae outbreaks. During the summer months when algae outbreaks are at their peak, “people should really be starting to pay more attention to their local situation,” Merrill says.

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