Christina Johnson, an animal behaviorist, with her dog, Moxie, a chow. The Providence Journal / Kathy Borchers

Roz Rustigian used to own a Doberman pinscher named Zoro, who was terrorizing her household.

The dog had been given up by a woman who could not handle him.

“When he came into my life, I posed a major problem for him because I was not the malleable type his former owner was. It was a clash of the Titans,” Rustigian recalled.

Zoro ate everything in the house. If Rustigian tried to talk on the phone, he would sit in front of her and bark. When she came into the house, Zoro would would leap up on the highest piece of furniture he could find, bare his teeth and growl at her.

Finally, in desperation, Rustigian called in Christina Johnson, a specialist in problem dogs, who also knows a lot about intimidating behavior.

Johnson, 40, is a 5-foot-11 roller derby queen who goes by the moniker Rhode Kill. By night, she rolls with the Rhode Island Riveters, Providence Roller Derby’s all-star travel team. She also skates as captain of another Providence team, The Mob Squad.

By day, Johnson is an animal behaviorist, working out of her home on a horse farm in rural Richmond. There are no fences there; her horses roam free.

An animal behaviorist is different from a trainer (although Johnson is both).

“Basically I diagnose and resolve behavioral problems,” Johnson said. “If a dog is growling, a trainer is likely to say, ‘OK, we need to correct the growling problem.’

“I go into a home and assess where the problem is stemming from. More often than not, it entails tearing down and rebuilding the social hierarchy of the household, and working with individuals.”

“Most of what I do is retrain the human members of the household,” she said. “Within the family unit, humans are a very giving species. They give privileges, they give gifts, they give treats, they give affection to show appreciation of their family members.”

But, Johnson said, dogs interpret all the attention as a sign of their dominance within the family. “Humans give a dog the wrong message, pushing the dog higher and higher in the hierarchy, which is often counterproductive….

“There are a lot of little things you can do to remind a dog that you rank significantly above it.”

Johnson started on her career path 20 years ago, when an aggressive chow-chow ended up at the pet shop where she worked. “She came in, and when I picked her up, she peed on me because she was petrified, and then she tried to rip my face off. I realized that she was not going to make it, so I ended up taking her home and working with her. She was very much a special needs dog, but she was a big catalyst for my behavioral education.”

That education included learning that a dog should never receive something just by asking, instruction Johnson passed on to Rustigian when working with her problem Doberman.

“You would give the dog a command, and only recognize the dog when it fulfilled the command. Until then, the dog didn’t exist,” Rustigian said. “The dog has to make the connection that all good things come through you at your discretion. It’s a complete flip of dominance.”

Johnson has another chow these days, and although it’s “not a common breed for obedience or therapy,” four-year-old Moxie is in training to do both jobs.

“A dog is born with a fixed temperament. It’s genetically pre-determined how dominant or subservient it will be,” but, Johnson said, “You can have some control over the outcome of that depending how you raise that dog. If it’s pushy, and you put a lot of boundaries on it, it will be a lot less pushy.”

It’s a matter of exerting control, not meting out punishment.

“There’s no corporal punishment, no yelling, never, ever, ever,” said Rustigian, who got a pair of rottweilers after Zoro died about 15 months ago. The dogs are well behaved.

“Christina is not a magician.” Rustigian said. Magic implies that the cure is a mystery, she said, while Johnson’s method is rational –– and clearly effective.

“I wish I had met Christina before I met some of the men I have dated.”

tmeade@projo.com