Shorty And His Allergies

People have allergies, in fact, I deal with outdoor pollen issues quite a lot.  Do dogs have allergies? Yes, they do...some have allergies to fleas that bite them and their skin is in distress, some are allergic to particular foods, and that's where my Shorty dog comes in.  I have noticed that he does extremely well on the dry food that I give him (prairie).  I have come to like several brands but it seems that they like the Prairie the best. I also give them wellness chicken stew because it's in tiny chunks and you can see the peas as well. Shorty loves this and does well on it.......however, I have noticed that on rare occasion, I have given my chis boiled chicken.  Shorty will especially scarf it down like it's nothing he's ever eaten before...but he ends up being sick the next day. Shorty has diareah and will not even eat the next day until it's almost time for bed. No matter if it's only a tiny amount, he cannot seem to handle it. He hides under the blankets most of the day until his tummy returns to normal. I guess that the boiled chicken will have to stop now that I 've noticed how it affects him, and there's no giving it to the other two without him because that wouldn't be too fair. ..so, no more boiled chicken for them.