The SPCA believes the city of Montreal's new restrictions on pit bulls and other dangerous dogs will result in many animals being euthanised.

The SPCA's Director of Animal Advocacy, Alanna Devine, said many people who are afraid of the new rules have contacted her agency.

"We have no idea what breed these dogs are and the way that the bylaw is drafted, it's technically any large dog with short fur could fall under this legislation," said Devine.

The city's revised animal control bylaw defines a pit bull as an American Pit Bull Terrier, an American Staffordshire Terrier, a Bull Terrier, a Staffordshire Terrier, any crossbreed with one of the above animals as a parent, or any dog that shares the physical characteristics of a pit bull.

The bylaw forbids the acquisition of new pit bulls within city limits after it comes into effect on Sept. 26, and gives pit bull owners until January to apply for a pit bull owner's permit.

Pit bulls would have to be muzzled whenever off their owner's property, and be on a leash unless behind a 2 metre tall fence or in a dog run.

The amendments also require all pit bulls to be sterilized and microchipped by Dec. 31, 2019.

Those rules would also apply to any dog that was determined to be dangerous, with that decision being made on a case-by-case basis.

The amendments come after a dog that was identified by police as a pit bull, but was registered as a boxer, escaped its yard and killed a woman in her backyard in June.

Devine said if the city of Montreal should adequately enforcing its current laws instead of making breed-based changes.

"That dog had bitten someone, sent someone to the hospital. There was a police report and there was legislation on the books that, had it been enforced, that dog likely would have been seized and that tragedy would have been prevented," said Devine.

The overwhelming majority of dog owners are scofflaws, with councillor Anie Samson saying that fewer than one in five dogs in Montreal are registered with the city.

Devine says the bylaw's ban of new pit bulls will lead to animals being euthanized.

"Many of the dogs we take in, we have no idea what breed these dogs are," she said.

Devine believes that people who want aggressive dogs will simply find another breed to mistreat.

"To think that if someone wants a dog for the wrong reason, to prohibit them from having a dog that looks a specific way, they are just going to simply go out and get another large rottweiler mix or great dane mix or be irresponsible and inhumane or abusively train that dog," said Devine.

When the legislation was introduced in city hall on Wednesday, Mayor Denis Coderre said that it was balanced and targetted all dogs that can be considered dangerous.

"For pit bulls you have to conform to certain rules. It's not euthanasia at large," he said.

He expects the bylaw will be challenged because of its criminal background restrictions.