Government officials are trying to determine whether blue-green algae caused the death of a dog that was swimming in the St. John River in Fredericton over the weekend.

In the meantime, health and veterinary officials are urging people to take precautions to protect themselves and their pets along the river and other recreational waterways.

"If you see anything or smell anything that's unusual, it's best not to go in the water," Dr. Cristin Muecke, the province's deputy chief medical officer of health, said during a news conference in Fredericton Monday.

"We do recommend as well that you don't swallow recreational water, that you rinse after you get out and that you don't go in if you have open cuts or sores."

Naturally occurring algae

Blue-green algae, also known as cyanobacteria, are photosynthetic bacterial organisms naturally found in rivers, lakes and wetlands. In warm weather, they can form blooms that may look like scum, foam or discolorations of blue-green, green, red, brown or yellow that can appear fluorescent.

Some blue-green algae produce toxins that can cause skin, eye and throat irritation, or gastrointestinal illness in people.

For pets, the toxins can be deadly within 30 minutes.

The young dog that died in Fredericton had been in and out of the water a couple of times on Saturday afternoon, said Dr. James Goltz, manager of veterinary laboratory and pathology services for the Department of Agriculture.

Within minutes, it vomited, got wobbly on its feet and collapsed, he said. The dog's owners were on their way to the vet when the dog went into convulsions and died.

Blue-green algae is "one consideration," said Goltz, but without being able to perform a full necropsy, he can't rule out other possibilities.

He hopes some stomach content samples collected from the dog will provide some answers and is looking for a lab to test them.

The province is also sending a team to the location where the dog had been swimming, off an island, to look for any clues, said Goltz.

Dr. James Goltz, manager of New Brunswick's veterinarian laboratory service, said dog owners should keep a close eye on their dogs in and around recreational water to ensure they don't drink the water or eat any vegetation. (CBC)

Dr. Colleen Bray, the vet who examined the dead dog, suspects blue-green algae was the cause.

She's urging pet owners to err on the side of caution and keep their animals out of rivers, lakes and standing pools of water until further notice.

If they think their pet has ingested blue-green algae, they should go to a vet immediately, she said.

Provincial officials are just raising awareness for now.

Safety recommendations

The St. John River poses no greater concern than any other body of water in the province, said Muecke.

Goltz recommends dog owners give their pet water to drink before heading to any bodies of water so the dog won't be thirsty. They should limit the length of time they're in the water and keep a close eye on them to ensure they don't ingest any water or eat any mats of vegetation, he said.

Algae mats, which look like clumps of vegetation, can be found in the water and along the shore. In the water, they can appear black, brown or dark green. They can be attached to rocks or aquatic vegetation or may be floating in the water. On the shoreline, they may appear brown or grey once they have dried.

Dogs are attracted to the odour.

Last July, three dogs in the Fredericton area died from the toxic algae after visiting the water's edge.

Two of the dogs died after eating some aquatic plants onshore at Carleton Park on Fredericton's north side. The third dog died after swimming near Hartt Island RV Resort, 14 kilometres west on the St. John River.

Prior to that, the last case of blue-green algae toxicity was in 2010 when a Labrador puppy died after swimming in the St. John River below the Mactaquac Dam in the Island View area.

Blue-green algae can also be harmful to livestock, wildlife and fish.