The xray pictured is not clean enough for me to really give an opinion... the right does, maybe, show a slightly smaller "ball."
I am not familiar with the Acana other than it is considered high quality. Thinking it is at least as good as the Hill's.
Perhaps adding some joint supplements rather than changing foods. Often, the dog food manufacturer (Acana) has a veterinary nutrionist on standby and will make suggestions if you call or email.
Last edited by gagsd; 09-20-2013 at 03:40 PM.