Have you tried raw chicken? My Angus, I thought, was allergic to chicken (he gets rashes and soft poop with any kibble that has chicken) but when I transitioned to raw, I tried raw chicken and he was perfectly fine with it! It could possibly be that it was some other ingredient in the kibble that he was allergic to and not the chicken like I thought or it could possibly be that he's allergic to the cooked version of chicken but not raw chicken. I'm not sure on this.
I mentioned this because chicken is one of the softest bones and is great for getting them used to processing raw bones. Rabbit is another one but if you don't have a reptile feeder supplier close to you can get expensive. The rabbit in the grocery stores near me is over $6 per pound whereas I can get whole frozen rabbit from the reptile expo for under $1.50 a pound.
I got Bullied and loving it!
Bella "Bullie" Rose, adopted on July 24, 2011