An Ontario man who killed a 200-pound black bear with a hunting knife says his faithful dog saved his life -- twice.

Tom Tilley, 55, of Waterloo, Ont., had been portaging last Thursday in northern Ontario near Wawa with his five-year old American Staffordshire, Sam.

He said they were walking toward the beginning of the portage to retrieve the canoe when he heard Sam start to growl.

"And I turned behind me and 20 feet behind me there was this black bear coming up the trail, sneaking up behind me," he said.

"If Sam hadn't growled, I may not have known until it was too late."

Tilley's first instinct was to try and make lots of noise and make himself appear bigger. He also started to slowly walk backwards, but nothing seemed to be scaring off the bear.

Suddenly, the bear took off down the portage path, ran through the brush and came onto the portage trail behind Tilley -- cutting off his escape route.

"At that point I kind of realized I might be in a bit of trouble."

"The bear seemed to me to be acting aggressive. I'm not a big guy and I could very well easily be prey."

At that point, his dog Sam placed himself perpendicular to the bear, across the path. The bear dug its teeth into the dog's back, and Tilley said he became enraged.

"I love my dog very much, and my first thought was, 'You're not going to kill my dog'."

"The momentary distraction that Sam provided to take the bear's attention away from me gave me the opportunity to run behind the bear, straddle its back and begin to stab it.

"I kept stabbing until it was dead."

He said Sam saved his life twice: "First by alerting me to the bear's presence coming up behind me and then again by placing himself between me and the bear."

After making sure the animal was dead, Tilley noticed he had suffered a wound to his hand and Sam had two puncture wounds. Tilley paddled for about an hour before he came across a couple of Americans who had a satellite phone.

They called for help, and a cargo plane came two hours later. Tilley and his dog were taken back to Wawa, where they were treated and released.

While Tilley credits his dog for his survival, he also said he recently bought the hunting knife after reading about a Cambridge woman who was killed in a bear attack last fall.

During the mauling that killed Jacqueline Perry, a young doctor, her husband had tried to fend off the animal with a Swiss army knife, the only weapon he had.

In a related development, the media interest surrounding Tilley's story helped him reunite with a son he had lost track of five years ago. His son had moved from B.C. to Alberta, and before he could tell him Tilley said he had moved as well.

"So he heard about the story and was able to make some phone calls and information was passed to me and we got together yesterday."

Tilley said he also got to talk to his grandson, who is now 10 years old.

"I tell you, when I first heard him say 'Hello papa' it was great."