A man has been pictured repeatedly throwing a greyhound into the sea before yanking it back out on a long line.
A witness said they were shaken by what they had seen and now the RSPCA is looking into the matter.
There were three men with nine muzzled greyhounds walking along a pier in Hartlepool, County Durham.
The witness, who was with his children, said: ‘They were being carried out to the end of the structure and unceremoniously flung in from a height of about 4ft and a distance, through the air, of 6ft.
‘The waves were quite strong and my first thought was, once they had surfaced, what if they were propelled by the crashing waves into the rusting sides of the pier?
‘There was a significant number of dogs in the group and it appeared that they were being taken out one by one.’
John Stephenson, who runs Greyhound Rescue North East, was shocked to hear what had happened and said he hadn’t heard of this practice before.
He said: ‘I have never heard of anything like this before, there is just no logic to it. Why on earth would anyone throw a dog into the sea like this in freezing cold conditions, it is just stupid.’
The RSPCA is urging anyone with information to come forward about what has been described as a ‘distressing’ incident.
A spokeswoman for the RSPCA, said: ‘We are still making inquiries after we received a concerning report that a group of men with a number of dogs were seen in Hartlepool repeatedly throwing one of the dogs – a greyhound – into the water on Thursday, November 2.
‘An inspector launched an investigation and attended the scene, but the group were no longer there.
‘Since then we have been contacted by a member of the public who provided photos of what appears to be a man throwing the dog into the water.