Animal welfare groups say dog-fighting rings are duping dog lovers into handing over their unwanted animals.

The warning follows a case this week of a family who believe their pet was stolen, potentially to be used as bait, by a dog fighting ring.

Buster's owners, Eileen and Michael Bray, of Erskine, fear he has been brutalised by thugs who took him to use in dog fighting.

He has yet to be reunited with his owners due to the effects of his ordeal, after being found earlier this week.

Linda Ess, founder of Lost Dogs Scotland, has warned people about using classifieds websites to give their dogs away.

She said: "People involved in dog fighting will place adverts on websites, saying they are looking to rehome a dog free. But these adverts are fake, they do not want to rehome the dog – they want to use the animal as bait for dog fighting.

"These people will go to great lengths to get their hands on dogs for free.

"Some will even bring children with them to pick up the dog, to give the impression the dog is going to a loving, family home.

"But that is far from the truth. I would urge anyone who is giving away their dog to do it through proper channels and use the Dogs Trust or Scottish SPCA.

"These organisations often have waiting lists and you may have to wait a little while before your dog is rehomed. But it is worth waiting to know your dog is going to a proper home."

Ms Ess, whose organisation helps reunite owners with their lost or stolen pets, added: "Dogs being stolen is a huge problem, particularly in Glasgow and the west of Scotland, and it is getting worse."

Jennifer Dunn, senior public affairs officer in Scotland for the League Against Cruel Sports, said: "Dog fighting is a horrific and cruel practice. It is tantamount to torturing dogs. It is illegal for good reasons."