UPDATE 4.55PM: The RSPCA has spoken with the family of a teenager who was photographed holding a knife to a dog's throat.
RSPCA spokesman Michael Beattie said the dog had not been injured and was in good health.
He said RSPCA inspector Penny Flaherty had attended the residence and spoken with the family, who said the boy had been made to do it.
Mr Beattie said the dog belonged to the boy's sister.
He said no further action would be taken.
EARLIER: A disturbing photo has emerged on social media, allegedly showing a Hervey Bay teenager holding a knife to a dog's throat.
The identity of the teenager is unknown, but the photo was shared to Facebook and soon went viral, causing an outcry from the Fraser Coast community.
Channel 7 shared the photo to their Facebook page and said they had spoken with the teenager's family, who claimed he was "forced" to do it.
They also said it was a toy knife and the dog wasn't injured during the incident.
RSPCA officer Penny Flaherty described the image as "disturbing".
She said she had not received an official complaint yet, but she was prepared to act if a complaint was made or if the identity of the teenager became known.
"It seems to be a silly hoax," Ms Flaherty said.
"Some thing just leave you speechless, don't they?
"This is disturbing behaviour from a young person."