Need more info please ?
1. Is the dog in a kennel ?
2. Is the tail bleeding most days ?

Suzy was a tail basher in her kennel. Went in the kennel one day blood everywhere, on the floor in the kennel, on the ceiling thought there was a mass murder going on.

Anyway took her to a well known greyhound vet. He suggested one of those old plastic granny curlers, taped the curl to the end of the tail. and that worked.

Then in the kennel I attached two pieces of timber one in the centre one at the bottom and attached hessian. Gave you this sort of look I( )I, so the greyhounds tail is not whacking against a mesh wall.

Personally I would try everything to save the tail, and leave docking as a last option.