Nutritional intervention is a critical part of managing disease. An appropriately formulate diet is has been shown to prolong survival time and improve quality of life in dogs with health concerns.
The very best diet for dogs with health concerns is one that is formulated for that individual dog.
A home-made diet provides flexibility in that the diet can be tweaked as to find the ideal diet to manage the condition long term. That sort of dietary flexibility is not possible with a commercially produced dog food.