Veterinary Behaviorists Note Continued Rise in Adolescent Dog Reactivity Cases
Veterinary behaviorists have continued to describe adolescence -- roughly 6 to 18 months of age depending on breed size -- as a period when previously well-socialized puppies commonly show new fear responses, increased reactivity to strangers or dogs, and a temporary regression in obedience reliability.
AVSAB's socialization guidance points to the narrow critical window early in puppyhood as foundational, but behaviorists note that adolescence is when many of those earlier gaps first become visible, since a growing dog's confidence and independence expose weaknesses that weren't apparent as a small, easily-managed puppy.
The consistent advice from credentialed behaviorists is not to panic or assume permanent damage: most adolescent regression responds well to a return to basics -- rebuilding calm, rewarded exposure to whatever specifically triggers the new reactivity, at a distance the dog can handle.
A full walkthrough of this exact pattern is available in this adolescent behavior regression guide.