Glossary

Fear period

A stage, often described around 8 to 11 weeks and again in adolescence, when a young dog may react strongly to things it once ignored.

Also called: fear imprint period, fear stage, adolescent fear period

Dog trainers describe fear periods as phases when a young dog suddenly becomes wary of ordinary things, such as a mailbox it passed every day. One is commonly said to fall around 8 to 11 weeks, and another during adolescence, roughly 6 to 14 months.

The idea is widely used, but research on exact timing is limited, and the pattern varies between dogs. What is well established is that bad experiences in young dogs can leave a lasting mark.

If a young dog is frightened, stay calm, give it space and let it approach at its own speed, with a treat but without force. Do not drag it up to the scary thing. Sudden or severe changes in behavior, especially in an adult, are worth a veterinary visit to rule out pain or illness.

Last reviewed November 8, 2026

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Related terms

Socialization Exposing a young dog to a wide range of people, animals, places and sounds in a positive way so that new things do not frighten it. Critical socialization period The early weeks of a puppy's life, roughly 3 to 12 weeks, when it learns most easily to accept new people, animals and places. Habituation A dog's learned reduction of its reaction to something harmless that is met again and again without consequence. Desensitization and counter-conditioning A training plan that exposes a dog to a fear trigger at a level it can handle while pairing it with something good, to change how the dog feels.