Have they tried giving her a shot of cortizone to help it heal and for the itching?

My sister had a poodle that use to chew and scratch all the fur off for as far as she could reach, the vet would give her a shot and she would stop for awhile... Just a thought, you may have tried it already.. Has she been spayed yet? I am sure she has but that is all it took to stop that from happening to the poodle.