Unfortunately the only way to diagnose a food allergy is by doing food elimination. Lame!
It sucks that there isn't an easier way.
Another thing worth trying as well, which I did for Napolean is Evanger's Game Meats. They have several different kinds of canned 100% meat bison, venison, rabbit, pheasant, duck, I fed those to Napolean with taurine supplement added, those are something you could try to rule out different proteins he's allergic to.
Also the holistic vet tried to tell me that it mattered whether the food was cooked or not and made me feed my cat raw chicken and Napolean who is allergic to cooked chicken is totally allergic to raw chicken, he's allergic to chicken in general! So for my cat I haven't seen a difference as far as whether it's in kibble form, raw form, or cooked form. If he's allergic to it, he's allergic to it.
It sucks that there isn't an easier way.
Another thing worth trying as well, which I did for Napolean is Evanger's Game Meats. They have several different kinds of canned 100% meat bison, venison, rabbit, pheasant, duck, I fed those to Napolean with taurine supplement added, those are something you could try to rule out different proteins he's allergic to.
Also the holistic vet tried to tell me that it mattered whether the food was cooked or not and made me feed my cat raw chicken and Napolean who is allergic to cooked chicken is totally allergic to raw chicken, he's allergic to chicken in general! So for my cat I haven't seen a difference as far as whether it's in kibble form, raw form, or cooked form. If he's allergic to it, he's allergic to it.