I not sure if this is what you are looking for, or if this will help, but I have used a product called Enervite, a nutritional supplement for non-eating and sick or elderly dogs, in the past.
They always seemed to love it and it usually stimulated a better appetite.
I no longer seem to be able to get it in the UK, and as my eleven year old Japanese Chin, Fonzi, is sometimes reluctant to eat & is now losing weight I am going to try Nurish-um dog paste and see if that will do a similar job....
Cavaliers......Tommy Tuppence 2000-2012 and a half share of Faith.
Japanese Chins.... Dandy, Benny, Bridgette and Hana.