The socialisation window in puppies lasts until about 12-16 weeks. Experiences during this period have lifelong consequences for welfare and behaviour.
Early socialisation is one of the most important determinants of long-term dog welfare, yet it is frequently neglected or poorly managed. The window of primary socialisation — when puppies are maximally receptive to new experiences — closes by around 12-16 weeks of age. Experiences during this period shape the dog nervous system in ways that influence behaviour throughout life. Dogs that miss appropriate socialisation are at dramatically higher risk of developing fear-based behaviour problems, anxiety disorders, and aggression, all of which cause chronic suffering and are common reasons for relinquishment and euthanasia. Responsible breeders begin socialisation from birth; puppy owners must continue this work systematically and positively during the critical window.