TORONTO - There are some problems even the Dog Whisperer can't solve.

Cesar Millan isn't allowed to bring his trusted sidekick, Junior, into Ontario -- the Liberal government banned pit bulls five years ago, saying the breed was too dangerous.

"It was a very difficult decision," Attorney General Chris Bentley said Wednesday.

"I mean, I have a dog myself. She's part of the family. But we heard many complaints from the people in the province. ... So we had to take steps."

Millan, a celebrated canine trainer and host of the popular TV show "The Dog Whisperer," rehabilitates aggressive dogs -- often with Junior's help.

He shouldn't be denied his right-hand companion as he crosses Canada for a speaking tour, New Democrat Cheri DiNovo argued Wednesday in an open letter.

"So once again, a responsible owner is being discriminated against because of the physical appearance of his dog -- not the dog's behaviour, but his looks," she wrote.

DiNovo even appealed to Bentley's office to make an exception for Junior, a three-year-old certified therapy dog that Millan adopted as a puppy.

Ontario's ban only makes exceptions for pit bulls that participate in dog shows and flyball, a dog sport involving a race with hurdles and tennis balls.

But Bentley wouldn't budge, saying Junior is not welcome in Ontario.

"I really respect the work of Cesar Millan, the work that he does," he said.

"You know why we brought in the pit bull legislation. It was to protect people and protect dogs -- protect other people's pets."

The grey-and-white pit bull mix has accompanied the Dog Whisperer on all his Canadian shows except the ones in Ontario, said NDP spokeswoman Marion Nader.

Millan even advertised Junior's participation in the tour, calling him an "ambassador" who brings "calm and balance" to dogs who need rehabilitation.

Millan was concerned that Junior -- who often helps him calm aggressive dogs on his show -- would be seized by authorities if he brought him into the province, she said.

After a member of Millan's staff contacted the Ministry of the Attorney General, an official wrote back, saying it couldn't provide any legal advice.

"There have been numerous horrific incidents that have happened in Ontario and elsewhere, in which people have been killed or severely maimed by pit bulls," the letter states.

"The government decided that the interests of public safety would be best served by restricting pit bulls under the Dog Owners' Liability Act (DOLA) to prevent more attacks and bites from this breed."

The ban applies to breeds considered to be pit bulls, such as Staffordshire bull terriers, or any dog that looks like one of those breeds.

Millan has often espoused his belief that dogs are not inherently dangerous, saying it's humans who often influence their behaviour.

He even dedicated an episode of his television show to dispel myths about breeds that are considered to be particularly dangerous, showing some of the toughest cases he's encountered and how the dogs have turned over a new leaf.