The white male Staffordshire bull terrier was found in Downside Park, Keynsham, on Wednesday 16 March by a member of the public who alerted the dog warden.
He was rushed to the RSPCA’s Bristol clinic where a vet and inspector Daniel Hatfield examined him.
His back legs were collapsed and he was unable to stand. He also had a serious skin condition and his nails were badly overgrown.
Sadly, the dog, thought to be around five-years-old, was in such poor condition that the vet determined the kindest thing to do was to put him to sleep to end his suffering.
Inspector Hatfield said: “This dog was in a very sorry state. He couldn’t use his back legs at all so his back end was collapsed.
“His skin was red and sore, and his nails were so long they were curling back on themselves.
“I suspect, as the dog wasn’t even able to stand, that he was dumped in the park and hadn’t made his own way there. I do not understand how anybody could leave any animal in this state.”
The dog was not microchipped so the RSPCA and dog warden are now making enquiries to establish who his owners are.
“I am looking for anybody who may recognise this dog or might know where he has come from,” inspector Hatfield added. “I would like to hear from anyone who may have information which could help us find the person responsible for leaving this poor dog to suffer.
“The RSPCA is always here to help and I would rather somebody phones us for help or advice than leave an animal to suffer.”
Anyone with any information should call the RSPCA’s appeal line on 0300 123 8018.