A short swim on July 4 in northeastern Alberta's Moose Lake proved fatal for Daisy, a nine-year-old springer spaniel.

After jumping over barricades, Daisy spent less than 30 seconds submerged in water with blue-green algae present before family members pulled her out and started to rinse her off.

"It was so fast," recalled Brittney Struck, who lives in Edmonton but was spending time at her parents' cabin on Moose Lake that weekend.

"As soon as she got out, she was green."

Within a couple hours, Daisy had thrown up and was coughing. She was taken to a veterinarian but died that night.

Struck told CBC News on Wednesday that her parents' dog was one of three to die in the region recently after exposure to blue-green algae. A neighbour of the family lost her dog in a similar incident and Struck said she learned of two other deaths from a local vet.

In a Facebook post last week, the Bonnyville Veterinary Clinic warned it had seen a number of cases stemming from contact with the bacteria.

Blue-green algae, also called cyanobacteria, are naturally occurring organisms found in bodies of water like lakes and ponds.

Some blue-green algae blooms produce toxins that, when the blooms die, can be released into the water.

The toxins can be harmful to humans, causing symptoms like skin irritation and sore throat. If consumed, they can cause liver damage, fever and diarrhea.

But the consequences can be "really severe" for dogs, according to Karen Marsden, a veterinarian who practices in Edmonton and California.

"It's very toxic to their liver and their neurological system," she said Monday in an interview with CBC's Radio Active.

Soon after exposure to the toxins, dogs can have seizures, affecting their ability to breathe.

They can also develop liver damage, with symptoms including vomiting and diarrhea.

Because the problems come on so quickly and many lakes in Alberta are isolated, getting veterinary care before it's too late can be difficult, Marsden said.

Treatment is possible, though it can take months and "huge amounts of money," she said.

Marsden advises pet owners to look for water warnings at lakes and stay away from water with visible blooms. Water with the bacteria does not always appear blue-green; sometimes it can look brown or rusty.

In addition to Moose Lake, Alberta Health Services has current blue-green algae advisories in effect for Lac Sante in northern Alberta, Lac Ste. Anne west of Edmonton and Islet Lake east of Edmonton.

The advisories warn against swimming in areas where the algae is visible, and consuming whole fish and fish trimmings from those lakes.