Fear can be manifested in a number of behaviors such as whimpering, going stiff, putting its tail between its legs, and also snapping or barking. If you think your puppy has been scared by a person, situation, noise, or anything else, walk calmly away from that trigger until your puppy is calmer and will take food again. If you feel your puppy is comfortable, reintroduce them to the trigger gradually and reward positive behaviors. If your puppy is still scared, remove them from the situation. Speak to a professional trainer or a vet if you are ever uncertain about your puppy's responses.