SUDBURY -- Petsave in Sudbury says it wants to alert pet owners in the city there have been five cases of parvovirus reported in the Sudbury area in the past four days.

Parvovirus is a highly contagious virus that causes gastrointestinal illness in dogs that can be fatal if untreated.

"We issued an alert to pet owners because this is a very deadly virus," said Petsave director Jill Pessot. "It generally affects puppies, however it can affect adults that haven't been vaccinated."

A Sudbury veterinarian said the Parvo vaccine is the best defence against the virus.

"Dogs can catch it from a contaminated environment, or (from) other dog's poop if there is a sick dog walking around it," said Dr. Morag Maskery from the Lockerby Animal Hospital.

"Dogs can ingest it and get quite ill."

Maskery said the Lockerby Animal Hospital has not treated any cases of Parvo so far this year. On average it costs about $100 a year to keep your dog up to date on vaccinations, she said.

"We have confirmed that the areas the four dogs came from are primarily the Donovan area, Minnow Lake and the South End on Pioneer Road," said Pessot. "So those are the current cases that are under care."

Maskery reminds pet owners the virus can be deadly if dogs don't get medical treatment.

"Your dog will get very, very lethargic, they really won't want to eat or drink," she said. "Vomiting and diarrhea is the main sign that you will see."

Petsave is urging dog owners to take precautions.

"Stay out of dog parks," Pessot said. "I would not bring your pets into pet stores and anywhere that pets congregate because if you have unvaccinated pets, they are at risk of contracting it."

Petsave said one of the five Sudbury area dogs infected with Parvo died over the weekend.