I admit, we groomers think we know a lot, but calling something a "dry patch" is certainly not a diagnose, only a description.
A dry patch can be from mange, from a hot spot, from excessive itching, from being shaved too close, and hundreds of other things. The scabbed edges are worrisome, those indicate some sort of irritation or infection.
I would certainly get this guy into a vet for a better idea of what you are dealing with, as well as some treatment suggestions.
Good luck!

Toto, CD, RN, CGC answered on 1/9/13. Helpful? / 0