The RSPCA is now searching for the person responsible after the Saluki-type lurcher dog was found with a head wound on farmland between Bewdley and Stourport.
A farmer cared for the dog until RSPCA officials arrived after finding it on land off Bewdley Road North on April 5.
The dog was bleeding heavily from its head and at first it was suspected that the dog had been involved in a car crash.
But when it was taken to a vet it was found that the injuries were not accidental and the dog had suffered a fractured skull, broken back and dislocated vertebrae.
The dog was so badly injured that the vet decided to put him to sleep.
'One of worst cases of cruelty'
RSPCA inspector Jonathan Ratcliffe said: “The dog was was found at 5pm, we suspect that he may have been used in an illegal activity - such as hare-coursing - the night before or in the early hours of the morning meaning that he had been left to suffer horrifically for many hours.
“The dog was in absolute agony it was awful to see.
"In my 12 years as an RSPCA inspector this is one of the worst cases of cruelty I have come across, to leave an animal in such a state of horrendous suffering is despicable.”
The dog was microchipped and contact was made with a previous owner, but as the details were not up-to-date there was no information on the new owner, who was living in the Bristol area.
Jonathan added: “The dog is a distinctive-looking tri-coloured lurcher who was emaciated and he was also wearing a red collar so I am hoping someone will recognise him and will be able to identify his latest owner who we are confident lives in the Bristol area.
“Also I am wanting to see if anyone saw anything suspicious on the night in question or saw any vehicles in the area which may help me trace the owner.”
Anyone with information should contact the RSPCA appeals line on 0300 123 8018.