Montreal dog owners are worried after new regulations came into effect on Saturday, based on what they say is a confusing and vague definition of a pit bull.

According to the new bylaw, a pit bull is defined as a dog “belonging to the American pit bull terrier, American Staffordshire terrier or Staffordshire bull terrier race,” or a crossbreed. The bylaw goes on to say that a pit bull can also be “a dog showing several morphological traits of the races and types.”

As of April 1, owners are required to follow a set of rules if their dog is deemed a pit bull. These rules include registering the dog with the city, completing a background check and keeping the dog muzzled, leashed and supervised in public.

Sabrina Mignacca adopted her dog Ivy two years ago from the SPCA and was told the dog was a pit bull mix. However, before the new regulations came into effect, Mignacca took Ivy to a city identification clinic.

“I did bring her to my vet and to the city ID clinic where she was deemed not a pit bull,” Mignacca told CTV Montreal. “So now she’s apparently a lab-greyhound mix.”

Mignacca said that even though Ivy is not a pit bull, the dog does have some characteristics that she worries could lead to a city inspector stopping her. This led to Mignacca taking a picture of the certificate she was given by the city, just in case she runs into trouble.

“Now it’s a whole new set of problems that I might be faced with,” said Mignacca. “Being stopped by animal control or even having people complain saying, ‘Hey that pit bull’s not muzzled,’ when she’s, in fact, not a pit bull.”

Montreal Mayor Denis Coderre spoke to reporters earlier this week responding to concerns from worried dog owners, only saying that it’s a matter of public safety.

“There’s a matter of safety but there’s a matter of common sense at the same time,” Coderre said. “Those who have a pit bull already can keep them but they have to respect some of the regulations.”

Several animal rights groups are fighting the new bylaw due to its breed-specific rules. Anne-France Goldwater, an attorney working on the case, said that the vagueness of the description of pit bull-type dogs leaves the owner vulnerable to the individual interpretation of an inspector.

“You’re very dependent on the whim or bad mood of a city inspector… that looks cross-eyed at your dog or at you and decides, well, that’s a pit bull-like dog,” she said.

Goldwater also said that there are some good parts of the bylaw, such as requiring a leash or harness for larger dogs, but that it should not be breed-specific.

The Montreal SPCA has said that it won’t be taking in or euthanizing any dogs that are seized by the city, and that they will instead be brought to rescue groups outside of Montreal.

With files from CTV Montreal