A while back I posted a thread on Misfires called: "How to get an extra five years out of you Gun Dog". It dealt with feeding your dog a natural diet consisting of 60% animal fat, 35% meat protein, and 5% organs.
Since then, one of my setters developed a tumor. I had allowed some carbs to creep back into his diet. Starting in January, I put him on a strict diet using the above macro nutrient percentages, and now his tumor has shrank 75%, to the point it no longer bothers him and he is able to act normally. Eventually, it should disappear completely. Proper nutrition is the key, both for canines and humans.
Regards
Ken