Provincial officials have determined the cause of death for two dogs in Fredericton which had been in or near the St. John River.
The New Brunswick Provincial Veterinary Lab says both dogs died following exposure to anatoxins which are produced by blue-green algae.
Samples were sent to a Halifax research facility for analysis after necropsies were performed on the animals.
Pet owners are being urged to keep a close eye on their animals near waterways and prevent them from drinking or swimming anywhere with green film on the water.
Experts say reducing the amount of time animals are in the water will reduce the risk especially for smaller dogs.