The weight-loss journey of a once morbidly obese Thai dog has taken it across the North Pacific Ocean to Ottawa, where veterinarians plan to cut away several pounds of its excess skin.

The story of Mercedes the mixed-breed street dog — so named because she was abandoned by a Mercedes Benz car owner — began in a Bangkok food market, where she was adopted by a food vendor.

When the vendor died, other vendors stepped in to help feed her.

"The problem is they pretty much almost fed her to death," said Geneviève Smith, one of the independent volunteers who worked to bring the dog to Canada.

Mercedes, a mixed-breed street dog, will undergo skin-removal surgery after losing nearly 30 kilograms. 1:26

The feast of fried food started to weigh Mercedes down, until she eventually became so obese she could barely stand. At that point, the vendors brought the food to her.

A dog her size typically weighs about 18 kilograms, but Mercedes — who is believed to be about five years old — weighed 54 kilograms at her heaviest, Smith said.

About a year ago, she was taken in by a woman who runs a foster home for dogs in Thailand, where Mercedes lost 27 kilograms — about half her body weight.

But her troubles weren't over.

She was burdened with excess skin, making her prone to skin sores and bladder infections.

Mercedes weighed 54 kilograms (about 120 pounds) at her heaviest. (Supplied)

Foster mother can relate

The Thai foster home reached out to global pet rescue contacts for help, and Smith was recruited to bring Mercedes to Canada.

She raised $1,000 through private donations to fly the dog economy class to Ottawa, where a local vet has agreed to do the surgery.

Mercedes arrived two weeks ago and is settling in with a volunteer.

"She is such a beautiful, calm soul," said Mercedes's Ottawa foster mother, Dacey Traill.

Mercedes lost half her body weight but still needs surgery to remove several pounds of excess skin. In Canada, she's been getting used to the idea of exercise. (Laura Osman/CBC)

She agreed to take Mercedes in after hearing the dog's story. Traill had gastric bypass surgery about three years ago and lost about 45 kilograms.

"I can relate to her and what it's like to be kind of heavy, not very mobile, not energetic, just not really loving life at all," Traill said.

"I think what spoke to me is that I can't imagine having all this extra skin and not being able to have the right mobility, even after losing all that weight."

Mercedes still has to lose another five kilograms before she can get her surgery, which means the dog that could barely walk a year ago is having to work up a sweat.

'Now she loves going out for walks'

Dacey Traill agreed to foster Mercedes in Ottawa. She shares a special connection with the dog, having lost weight herself. (Laura Osman/CBC)

For the first time in years she's going for walks, and though the concept seemed foreign to her at first, Traill said Mercedes has come around to the exercise.

"I wasn't sure if it was that she wasn't sure what a walk was or just unsure of what grass was, but she was pretty hesitant," she said.

"Now she loves going out for walks. She prefers being outside."

Geneviève Smith volunteered to raise money to bring Mercedes to Ottawa and is raising money for the dog's surgery as well. (Laura Osman/CBC)

Traill is also planning to get the dog a life jacket so she can start swimming.

Meanwhile, Smith is working on raising $3,000 for the surgery.

Not going back to Thailand

As for why she believes it's worth going to such extraordinary and expensive lengths to help a dog a world away, Smith said she gets that question a lot.

Mercedes will be looking for a new home in Canada once she's recovered from her surgery. (Laura Osman/CBC)

"People have the same arguments about foreign aid," Smith said.

"I think it doesn't have to be one or the other. We can help all these sweet animals from all over the world. They're all deserving of a better life."

Once the surgery is complete, Mercedes won't be flying back across the ocean to Thailand.

Volunteers will work to find her a new forever family in Canada, Smith said.