My dogs love the squirrels in the tree trunk toy. You stuff the squirrels in the trunk and they have to get them out. Doesn't take them long to learn. I bought the Junior size, but they sell replacement squirrels for the regular size. I could use some more squirrels. They are my dogs favorite toys -- just the right size and easy for them to squeak.
Junior Small Hide a Squirrel Puzzle Dog Toy for Small Dogs It also comes with bees in a hive, birds in a birdhouse, and maybe something else.
Any talking toys are a hit with mine:
Talking Dog Toys
They had a monkey that made monkey sounds that they LOVED! They only recently dug the voicebox out of their monkey. I need to find another one.
I made a score at Walmart one year -- they had these toys in the kids toy department that you slam and they say all sorts of things. They marked them down to a dollar each -- I bought like 20 of them and shared with family dogs! The furkids LOVED those things. I also bought a bunch of the old Taco Bell talking chihuahuas on ebay. My pups seem to love any toy that makes unique sounds or talks. They love squeakers too but they really go crazy for talking or monkey sounds.
