Hi,I also have a fussy gsd bitch,when she first went fussy I took her to the vet and she had what they said a secondary infection,she healed and ate well again up until her first season,too her back to vet incase she had this infection again and she was fine,they thought she might have been preg which I nearly died but thankfully she's not so anyway she has remained fussy I started putting some tin pal food in with her biscuits,about a table spoon or two and she eats that quite well,although I have started her on missing link and sprinkle that on her food and she is eating her meals with that on top.