No action is to be taken against people responsible for throwing greyhounds into the freezing sea at Hartlepool after an RSPCA probe due to a lack of evidence.
The RSPCA carried out a full investigation, but now says there was not enough evidence to lead to a prosecution.
A spokesman said: “The RSPCA inspectorate fully investigated this matter with the evidence that was supplied by members of the public.
“Interviews were conducted and witness statements gathered and referred to the RSPCA Prosecution Department.
“The evidence was reviewed by the RSPCA Prosecution Department in accordance with guidance in the Code for Crown Prosecutors.
“In order for a prosecution to be brought against an individual, there must be sufficient evidence to prove that individual was responsible.
“In this case, despite extensive investigation, it was decided there was insufficient evidence to proceed.
“Despite this, we would like to thank people for their concerns and we would not condone such treatment of animals.”
The RSPCA received two reports relating to different days of greyhounds being thrown in and out of the sea which investigators believed to be connected.
Mail readers previously blasted the cruelty of the people responsible.
One commentator suggested they may have been doing it as rehabilitation for racing dogs to help muscle repair and strength.
But David Parker, a member of the Northern Counties Animal Protection Society, said: “To me, it seems absolutely unbelievable that you would throw a dog into the raging sea in winter just to tone up its muscles.”
In one incident a member of the public said they saw three men with nine muzzled greyhounds at the sea, through the Brus Tunnel area of the town.
After walking out on a structure into the sea, one of the men was seen repeatedly throwing a dog into the water and yanking it back out on a long line.
A second person, who was some distance away with his children, passed on photographs of the incident.
The witness, who did not wish to be named said at the time: “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?”
CAGED, the Campaign Against Greyhound Exploitation and Death, previously said incident could easily have killed the dog.