A cross-country odyssey has ended for a dog that has been reunited with its Montreal owners after being found thousands of kilometres from home.

The  thrilled Robitaille family greeted their dog Pollux at Trudeau airport Thursday night.

"We had a hard time. We couldn't  forget her and we cried when we heard she is coming back," said Isabelle Robitaille.

The Labrador mixed-breed dog disappeared in 2010 and ended up in Kamloops, B.C – about 4,500 kilometres west of its home.  

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The Montreal Labrador mixed-breed disappeared last year and was found some 4,500 kilometres away, in Kamloops, B.C. (Canadian Press)

Exactly how Pollox  travelled to the West Coast remains a mystery, but an SPCA office there was able to track down the owners in Montreal thanks to a microchip embedded in the dog that stores information.

"I am a big big fan of these microchips," said Robitaille, offering advice to other pet owners.

"Go chip your dog, see my story, go chip your dog."

The SPCA in Kamloops, B.C., said it puts chips in all of its animals before they are adopted.

"We can tell which company the microchip belongs to so we can just call the corresponding company and they tell us who the owner is," said Kamloops SPCA official Sarah Gerow.

On the day Pollux disappeared from the Robitaille's backyard in 2010, it had been raining and Robitaille suspects the dog, that is afraid of water, might have hopped onto a freight train to avoid the rain but she said it's also possible that Pollux was picked up by a trucker or a family heading west.