The dog needs a neck cone. The biting is what they are for.
+1
Call the vet and find out how much it runs to rent one for a week until the owner comes back.

Our German Shepherd would go through biting phases every couple of years. Some times it was dry skin (Winter) sometimes bugs and sometimes because she just plain enjoyed chewing all the hair and hide off her back!
She chew it, then it would get infected and we'd have to take her to the vet. The vet would shave her like some deranged Mr. T looking thing and in the cone she'd go for a week.