My dog developed a food allergy at 6 months, so i think they can arise at any age?
Hes now on hills z/d and much better.
I have 2 bengals, the only food that suits them is pets at home dry, everything else upsets them. They get into everything and occasionly eat something they shouldnt, if they get a runny tum i give them hills i/d pouches, its always done the trick for me.
hope this helps a little