RUMOURS of a dog-fighting ring in Launceston's northern suburbs have terrified pet owners who say they are worried their pooches could be nabbed for use in the blood sport.

Flyers warning of a gang of youths allegedly paid to steal dogs for fighting were dropped in letterboxes at Ravenswood and Waverley this week.

But police and animal welfare groups say they have no evidence that the illicit trade is taking place.

Kaitlin Riley's 14-week old pit bull terrier, Timon, was taken from her Rocherlea home in a burglary on December 21. Her cousin bought him back for $50 off a man on a Ravenswood street the next week.

``There are dogs going missing all over Ravenswood,'' Ms Riley said.

``It's beyond a joke. These dogs are like children to some people.''

Kathy Mason's Maltese terrier went missing on December 16.

The Ravenswood woman says she is worried the dog, Toby, was taken for use as bait in a dog-fighting ring.

``People contacted me on Facebook and told me that's what it was, and that a 14-year-old had admitted to taking it,'' Ms Mason said.

``I cried for about three days.''

Ms Mason reported Toby's disappearance to police and was told they could do little without proof that he had been stolen.

Launceston police Senior Sergeant Mike Gillies said dog-fighting was a persistent rumour in Launceston.

``While we have heard a number of rumours, we are yet to come across any actual evidence that such things are happening in the Launceston area,'' he said.

``Anyone who has direct evidence relating to such things as this should contact police immediately.''

Senior Sergeant Gillies said police had only received two reports of missing dogs in 2012, and none of stolen dogs.

Residents say a dog-fighting ring is the most likely explanation for the significant number of dogs that have disappeared in recent weeks.

The same phenomenon was reported this time last year.

RSPCA deputy chief inspector Scott Byrnes said reports of dog-fighting commonly surfaced on social media but were yet to be substantiated.

``The validity of these claims is often very poor - it's always a friend of a friend of a friend,'' Mr Byrnes said.

``It's something that we intensely investigate.''

Anyone with evidence of dog-fighting can contact the RSPCA animal cruelty hotline on 1300 139 947 or Crime Stoppers on 1800 333 000.