
How sad, poor thing. Just a thought have you changed your washing powder that you wash his bedding in? Biological powder can cause skin problems, probably best to change to non bio just in case.
I assume the hepatic diet he is on didn't coincide with the onset of this, skin problems are often caused by diet. If he need to be on this then my suggestion on trying a bland human quality diet of mince, chicken, rice or pasta wouldn't be much help.
Hope you find something to help, it must be very distressing to see an elderly dog like this
Sandra