Loki Love, sorry to hear about your kitty.
I agree with sugarcatmom and not discuss Mr Miyagi's diet with your vet .....just tell her you're working with a feline nutritionist and not interested in any food made by Hills.
Here is what the dogfood analysis site says about the z/d dog food ....
http://www.dogfoodanalysis.com/dog_f...uct=1078&cat=7
Two other members here have this same problem with their cats (Chris21711 and quincymycat) and I'm sure they will post what has helped them once they log on.
Good luck.