Have you tried the plush activity toys? There's one that looks like a tree stump with 3 holes in it and it comes with 3 or 4 plush squeeky squirrles that you stuff inside -- goal being that he/she retrieve the squirrles out of the tree. Sounds weird when I describe it I think, but I know many-a-puppy that loves this toy!! Not to mention the entertainment factor on our side! I dunno, just a suggestion!
good luck.