Three dogs that quickly died after being in or near the Saint John River were killed by toxins found in a type of blue-green algae, New Brunswick health officials confirmed Friday.
Witnesses say two of the dogs suffered convulsions and vomiting after playing near the water at Carleton Park near Fredericton on July 22, and another dog died July 20 after swimming in the river near Hartt Island campground, about 10 kilometres from the park.
New Brunswick’s chief veterinarian, Dr. James Goltz, told a news conference that necropsies on two dogs determined all three died following exposure to anatoxins, the toxic substances produced by cyanobacteria, which are commonly known as blue-green algae.
He said samples of water, algae growing on rocks, and mats of vegetation – both onshore and on the water – were collected by staff with the provincial Environment Department. Those samples were sent to the National Research Council for testing.
“All samples contained anatoxins, but the levels were particularly high in the samples from vegetation mats and the stomach contents of the dogs submitted for necropsy,” Goltz said.
WATCH: Officials suspect algae cause dog deaths at Fredericton park
He said the two dogs that did not enter the water somehow ate aquatic vegetation that had washed up on the shore.
Dr. Na-Koshie Lamptey, regional medical officer of health, said people should always be careful when entering natural bodies of water, but that doesn’t mean people should avoid swimming in the river.
“To be clear, while it has been determined that blue-green algae is present in some areas of the Saint John River, we are by no means saying that you can not continue to use the river for recreational purposes such as swimming,” she said.
“The river is vast, flowing and always changing. It is likely that any presence of blue-green algae is intermittent.”
However, Lamptey said water should be avoided whenever there are abnormal smells or colour. As well, all bodies of water should be avoided if you have open wounds or cuts, she said.
However, even if the water appears clear, it shouldn’t be swallowed – and bathing shortly afterwards is always recommended.
“As conditions change frequently in natural bodies of water, there is always a risk that comes with their contact,” she said. “By following these general precautions, the risk of being exposed to biological hazards will be reduced.”
Lamptey offered her condolences to the families who lost their pets.
“It is not lost on us that these animals are important members of New Brunswick households and we know it has been a difficult time waiting for answers about what led to their deaths,” she said.
According to the National Collaborating Centre for Environmental Health, blue-green algae can occur in Canada at any time of year, and the microscopic organisms can be found in fresh, brackish or salt water.
However, only a very small proportion of cyanobacteria produce toxins. Between 80 to 100 different compounds have been discovered in these blooms, and all have different levels of toxicity.
The toxins have similar effects on humans and animals, and they’re generally grouped into three classes: those that affect skin; those that affect the liver; and those that affect the nervous system.