Are you seeing movement of the leg bone where the scrape or ring is around the leg? It may well be broken, and the blisters could be related to the splinting. Sometimes when splinting is done, the vet wrap or tape becomes too tight, and the circulation is interrupted. Can you try to get an X-ray? If you resilient, be sure to pad it well. Check the circulation. I would be tempted to leave it off. There have been a lot of leg and foot damage or amputations on legs that have been splinted incorrectly.