In the past few months, the Illawarra Mercury has received multiple phone calls from concerned dog owners who say their pets have gone missing, and Facebook reports have suggested they have been stolen to be used in "dog fighting rings".

Several residents reported finding coloured markings on their fence after their pet disappeared, and claimed it was the calling card of the syndicate responsible.

However, RSPCA NSW chief inspector David O'Shannessy said while dog fighting rings might exist, most of these reports stemmed from misinformation being spread via social media.

"Many of these reports utilise the same hoaxes to incite fear with pet owners," he said.

"Every day we seem to receive a question about dog fighting in an area of Sydney or NSW.

"Many of these are well-known hoaxes that have been created by and continue to be circulated via social media. We are not saying that dog fighting doesn't happen, or that it isn't happening, we're just asking members of the community to be vigilant and recognise hoaxes."

The RSPCA said markings on fences could exist for a variety of reasons, and the organisation had received no reports of dog fighting in the Illawarra.

Mr O'Shannessy said the ribbon hoax began in Perth before being spread via social media.

He also said there was no factual base behind a second hoax, which involved the sharing of a photo of reported dog napper Dell Schanze.

"Mr Schanze is a real person, living in Salt Lake City, Utah, and there has been no evidence to link him with dog fighting," Mr O'Shannessy said.

RSPCA NSW encourages anyone with any information pertaining to dog fighting to contact 1300 CRUELTY (1300 278 3589).