These toys can be filled (or smeared) with wet food or treats like peanut butter, cream cheese or liverwurst. They're a great way to give your dog's tongue, and brain, a workout! The Kong is the most famous toy of this type, and hence lends its name to the whole category. However, out of all the toys of this style, it can be the hardest -- it can be difficult for your dog to get the food out of the narrow tip. For this reason, we generally suggest using it only for treats, or filling it with dry food and then creating a plug at the end with a dollop of cream cheese. Most of the other toys in this collection, however, can be used with any type of wet food.