I used to offer Princess a Kong all of the time as a pup & she'd have nothing to do with them. Now in her little "deprived" world, she loves it!
I tried again so she'd have something to look forward to when I leave & she gets so excited about it! She'll start "talking" to me to get it as soon as I start putting my shoes on so I don't forget.
I fill hers with I/D canned & lately have been putting a little baby food in the middle (swt. pot. & chick, which is vet OK'ed) then freezing it. When I get home one of the first things she does is ask me to fill it again, which I don't so it will stay "special".