My last dog (West Highland terrier - 18.5yrs old when she passed on) was initially a high maintenance dog - she was 4 yrs old when we inherited her from the father-in-law when he passed on) with a skin condition that smelt to high heaven. Medicated shampoos and vet prescriptions did nothing to solve the problem, they only masked it. Stop the treatment the problem resurfaced. it was eventually cured by a diet change to one that was composed of raw vegetable and fruit matter (peelings and offcuts from the kitchen, rough blended, not pureed, together in a blender -no onions or potatoes or orange peels) coupled with tinned tuna. That was for the evening meal. In the mornings she was given a raw chicken wing or leg to munch on to keep her teeth in good condition. As she was only a little dog 7.5-8Kg. I only had to make the food up 1 or 2 times a week , as it didn't matter that even though it was kept in the fridge it was slightly "off "after 3 days she couldn't get enough of it. She was on this diet for the last 10 years of her life. Her skin condition cleared, once we found that it was diet that was causing her condition (prior to this the vet had her on a 1/2 cortisone tab/day which cleared the skin but made it as tight as a drum).
Basically she ate what we ate in the form of vegetables and fruit. The only bad effect of this was after her meal she smelt a bit fishy but that was all. Before the diet change there was always food left in the bowl, after the change she licked it to within an inch of its' life, every meal for over 10 years. The other side effect was that I lost my compost bin as she became the household food composter.
The diet change came about because a locum vet mentioned(on a regular vet check up) how dogs were being fed the wrong food as their ancestry was that they were a scavenger animal which usually fed on the remains of carcasses left by the top order predators - basically stomach contents - which in prey animals is mainly vegetable matter. Whatever, it worked for her. Just thought that it may be of interest to you.