I'm glad the spray cheese is working as a back-up for you. Have you tried Carolina's trick using the soft Whiska Lickin's yet? That one works for me once in awhile. Also, once in awhile I can get away with using a Greenies Pill Pocket, but I have to smoosh it up first because the 1/4 pill still won't even fit in it, After I smoosh it up, then I can wrap it around Sven's 1/4 pill. I can't tell you how many of his "spiked" treats have been thrown away because he won't eat them! He has refused "spiked" hot dogs, spray cheese, cream cheese, liverwurst, motzarella cheese, and I think something else but I can't remember right now! I was wondering, though, HOW you hid it in tuna. Are you talking about an actual tiny piece of raw tuna steak? Otherwise, how would you hide a pill in a piece of tuna that comes in a can? Isn't that flaked? (just curious, because I'm getting desperate here!)