A Ladner, B.C. family is fighting to have their lost dog Cleo returned after finding it with another owner in Vancouver last week.

Jamie Gillespie says he and his daughter were devastated when their border collie cross went missing four years ago, but always believed they would somehow see her again.

"I took Cleo to work with me every day," he told ctvbc.ca. "She rode next to me, she spent all day, every day with me."

On Tuesday, Gillespie was driving along Cambie Street when he saw a dog with an uncanny resemblance to Cleo tied up outside a grocery store. He pulled over and waited for the dog's new owner.

"I'm not about to take the dog away illegally, I just want to be able to see her," he said.

The owner claims the dog was adopted from an Abbotsford animal shelter, and refuses to return her. But Gillespie says he's certain the dog is Cleo, and that a tattoo in her ear would trace it back to his veterinarian – except that one letter is wrong.

"The police are saying that the tattoo was done in error," he said. "They say the shelter wasn't able to trace her back to me. But it was a matter of two possible phone numbers they had to try calling, and that was it."

Gillespie says he's suspicious of how the dog got from Ladner to Abbotsford in the first place, and is considering legal action against the shelter for not trying harder to locate him.

He says he'll also continue fighting for the return of his dog, which is now seven years old, if the new owner doesn't want to cooperate.

"If she would allow us to see the dog, allow my daughter to see the dog, I might not be so intent on putting up a huge fight," he said.

"I understand her connection to the animal. She's a loving dog and I can see why anybody wouldn't want to give her up."