Here's a great toy by Nina Ottosson's toys, she has a great line of toys for those clever dogs in your life. She has a series of toys and gadgets that consist of interlocking pieces that slide, move , or rotate to allow your pet to work for those treats they so much enjoy and deserve. The price is a little high on these but it is well worth the money and these are very durable interactive games. How this toy works is the treat are located under those sliding bones and you can't take them out so your dog must figure out how to move them with his paws or nose.
I give this toy 7 paws out of 10