My dog is a very energetic and intelligent JRT/chihuahua mix. She's 11 years old, but the only sign of her age a few gray hairs. Anyway, she typically only plays with plush squeaky toys, but occasionally I'll find a treat-dispensing toy she'll be interested in. She isn't a big chewer, so she didn't care about the plug, but I've been putting bits of some of her favorite treats inside and it's kept her busy for a while. She has no interest in the toy when it's not filled with treats, but when it is it's one of the better toys I've gotten for her recently.
The material for these Everlasting toys is squishy but they hold up to powerful chewers very well. I dont use the treats designed to fit in the ends as my dog is able to remove them in seconds flat and I believe it poses a choking hazard since she is so big. Overall- love it.