Send one camper outside and explain to him/her that they are going to act like an animal when they return to the group and that they aim of the game is for everyone else to guess the animal. Tell them to be a dog.
While the camper is outside the rest of the group is told that they must not guess that the camper is a dog when he returns. They can guess any other animals but not dog.
After 5 mins tell the person in the middle acting like a dog to pick a new animal and then while they are acting as this animal, keep guessing that they are a dog.