Puppy weeks 8–10

Puppy weeks 8–10: First Fear Period

Weeks 8–10 are a puppy’s first fear period. The brain is primed to imprint scary experiences strongly, so a puppy may suddenly startle at things that never bothered them before. It’s normal and it passes. Go slow, never force scary situations, and pair anything new with treats.

When does this happen?

All breed sizes	Weeks 8–10

Not sure this is your puppy’s exact stage? Check the Puppy Stage Finder. Wondering if sudden fearfulness right now is normal? Get a straight answer.

Common questions

Why is my 8-week-old puppy suddenly scared of everything?

Around weeks 8–10 puppies enter their first fear period — a normal developmental window where the brain imprints frightening experiences more strongly. New wariness or clinginess is a phase, not a personality change, and it passes.

What should you avoid during a puppy’s first fear period?

Avoid forcing your puppy into frightening situations, punishment- or flooding-based classes, and overwhelming events. A single scary experience can leave a lasting mark during this window.

Grounded in established canine behavioural science — see our sources.