An ad on Gumtree warns against advertising pets for free. Larger breeds would be starved and tormented into brutal fighters, while their smaller counterparts would be used as "bait", according to another popular Facebook post. An image warning people of a system, in which red squares were put outside homes to alert canine thieves to a potential candidate, was uploaded to Facebook and shared more than 9000 times on Tuesday. "These red symbols are tags that people stealing Perth dogs are putting on your gates/fences," the post read. "These tags identify which house has a dog that needs to be collected later that day/night by these disgusting creatures.

A photo shared on social media is captioned: “These red symbols are tags that people stealing Perth dogs are putting on your gates/fences. These tags identify which house has a dog that needs to be collected later that day/night.” "Be vigilant!" An advertisement posted on the online classifieds website Gumtree on Wednesday also warned of listing pets online for free, because, according to the Osborne Park woman who posted the warning, they were unlikely to go to a good home. "There is currently an organised dog fighting ring in Perth," the woman wrote. "Stealing dogs from backyards north and south of the river!! Free dogs will be taken by them!! They are also stealing and collecting free cats guinea pigs and rabbits to use as bait to entice fighting!

"Please don't advertise as free!!" But animal welfare authorities in Perth, who have been inundated with phone calls since the messages started to appear about two weeks ago, said the warnings were "completely unfounded" on Wednesday. "It's a viral hoax," RSPCA spokesman Tim Mayne told Fairfax Media. "Police and the RSPCA have no solid evidence on this at all. "We've been monitoring this situation for the last week and a half and still, to the best of our knowledge, it's a viral hoax." He said there had been various dog fighting hoaxes spreading around the world in recent years.

Curtin University internet studies lecturer and social media expert Tama Leaver said the lack of specific details in the messages was a dead giveaway for a viral hoax. "If people were really trying to stop something there would be specific details about it and who they could contact," he said. He said the messages were so vague they had managed to cover "the entire spectrum of Perth". "If something like that is appearing for two weeks and there's no official information released whatsoever – there's no police follow up – and there's no evidence of an actual fight, you'd have to question it," he said. "To go from dog missing to dog fight is a long bow."

Mr Leaver said viral hoaxes were the "downside" of social media, which had become a great source of quick but "rarely verified" information. We tend to be more gullible online, he said. "Unfortunately our instinct to verify information online is very low." Online hoaxes tended to be motivated by money or individuals who are "just trying to get a rise," Mr Leaver said. Then there were those who believe they're teaching the world a lesson by testing how far unverified information could reach, he said. Once the message found an audience like animal lovers or pet owners, the heavy lifting was done for the pranksters, Mr Leaver said.

"Things will circulate because you do have some people who believe the police lie and will want to keep saying this is true," he said. "Look at something like climate change: all the science says this happens, but there are still people online saying it is a lie," he said. While Mr Leaver said he was "99 per cent certain" the message was a hoax, Murdoch University cyber forensics and information security lecturer Richard Boddington said there was still a remote chance somebody out there had tried to send a real warning to pet owners. Loading But Mr Boddington also warned there could be a follow up message in the coming weeks asking concerned residents to donate money to stop the dog fighting they've all heard so much about.

"Or it's probably just somebody trying to stir the pot," he said. Follow WAtoday on Twitter