It's really only during the transition from weaning that you might soften the food, as puppies don't have the teeth development they need yet. By the time they are eight weeks old, most dogs have proper teeth for puppy food, which is going to be smaller in size and easier to chew. As they get older, know that variety is a good idea when feeding your dog.You want to be giving them canned food and dry food so they can experience both and get used to it.