The puppy that was reliably sitting and coming when called at 4 months looks up when you say its name at 8 months, registers your presence, and then looks away to continue investigating the smell on the fence post. It was doing so well. You were doing so well. And now it seems like all of it has evaporated and you’re back to a dog that treats training as optional. You’re not imagining it. It’s a developmental phase and it has a name.
What’s Actually Happening
Adolescence in dogs typically starts around 6 months for small breeds and 8 to 10 months for larger ones. It lasts until roughly 18 months for small breeds and up to 2 years for large and giant breeds. During this window the brain is undergoing significant reorganization — the prefrontal cortex, the region responsible for impulse control, decision-making, and social interaction, is still developing. This is why adolescent dogs are more impulsive and often seem to overreact to situations that didn’t previously faze them.
The amygdala — the brain’s emotional processing center — is running at high volume during this period with less inhibitory regulation than usual. The result, as Preventive Vet’s trainer notes, is that adolescent dogs have “BIG BIG feelings” — good feelings, bad feelings, fear, excitement, everything amplified to maximum. The dog isn’t being difficult. It’s running a neurological renovation project and doesn’t have full access to the skills it had before the construction started.
There’s also a documented phenomenon that most owners experience as a personal slight: a recent study found that teenage dogs tend to respond better to other people than their owners — even complete strangers. The dog that’s a star at training class with the instructor but acts like it’s never heard “sit” from you at home isn’t being selective out of spite. Adolescent dogs are in an independence-seeking phase. It’s the canine version of the teenager who rolls their eyes at their parent but behaves perfectly for other adults. It’s not about you.
The Second Fear Period and Secondary Chewing
The second fear period — usually hitting between 6 and 14 months — is part of adolescence. A dog that was confident and social at 5 months may suddenly become reactive on walks, startled by things that didn’t previously matter, cautious around strangers. Handling this the same way as the first fear period: no forcing, no punishment of fear responses, positive exposure at sub-threshold distances, consistent calm routine. Forcing a fearful adolescent toward something that frightens them creates impressions that last much longer in this window than they would have earlier.
There is also a secondary chewing phase between 8 and 10 months as the adult teeth settle into the jaw. Owners who breathed a sigh of relief when the teething chewing slowed at 6 months sometimes find renewed destruction around 8 to 9 months and think they’ve done something wrong. They haven’t. The appropriate chew outlet strategy from the teething phase applies again: frozen options, rotation to keep things novel, access management for anything that shouldn’t be chewed.
What Actually Gets You Through It
Don’t stop training. Return to basics. Training in adolescence often feels futile because the dog seems less responsive than before. The response is to go back to lower distraction environments, higher value rewards, and shorter sessions — not to stop training because it’s not working. The behaviors haven’t disappeared. They’re less accessible during this window and need more support to fire. Practice in real-world situations where the dog can be successful, and gradually work toward more distracting environments. Ending sessions on success, even small ones, keeps the training relationship intact through a period that can otherwise become adversarial.
Management isn’t giving up. Adolescence is a prime time for bad habits to develop. Crates, baby gates, and other management tools prevent the dog from rehearsing behaviors that would be problematic in an adult. A dog that can’t get to the counter doesn’t practice counter-surfing. A dog on a long line in the park can’t rehearse ignoring the recall. Management doesn’t replace training — it protects training by preventing the wrong behaviors from becoming practiced patterns during a period when the brain is particularly good at forming new associations.
Rethink exercise. The instinct with an adolescent dog is to tire them out with more physical exercise. Over-exercising tends to backfire: what results is a super tired but overstimulated dog who is also getting more conditioned to needing a higher amount of exercise. Mental exercise wears out an adolescent dog faster than physical exercise. Short training sessions, sniff walks, puzzle feeders, and problem-solving games produce a more settled dog than additional miles on the leash.
Don’t take the independence personally. The adolescent dog is supposed to start orienting toward the world rather than entirely toward you. That’s developmentally appropriate — it’s how dogs develop the autonomy that adult dogs have. It doesn’t mean the bond is broken or the training is undone. It means the dog is going through a phase that every dog goes through, and the work is to stay engaged without escalating every cue refusal into a confrontation.
Maintain the routine. The adolescent dog that challenges previously established rules — trying to dart through doors, jumping on furniture again, pulling on the leash — isn’t being willful. The idea to try the alternative just popped into their head, so they tried it. Calm, consistent, non-reactive correction of rule violations — redirecting rather than punishing — keeps the boundaries clear without making the relationship hostile. The rules don’t change because the phase is difficult. Consistent, mild enforcement during adolescence prevents the rules from disappearing entirely.
When to Get Help
Adolescence produces difficult behavior. It doesn’t excuse genuinely unsafe behavior. A dog that is developing reactivity — lunging aggressively at people or other dogs, resource guarding with intensity, or showing fear-based aggression — during adolescence warrants a consultation with a certified trainer or veterinary behaviorist rather than waiting for the phase to pass. Adolescent behavior that isn’t addressed sometimes becomes adult behavior that’s much harder to modify. The phase is a reason to get support, not a reason to wait.
It ends. Adolescence is a transitional phase between puppyhood and adulthood — the brain rewires and the hormones settle. The dog at 2 years old is genuinely different from the dog at 9 months. The owner who maintained structure, kept training going at a lower bar, managed the environment, and didn’t catastrophize every difficult interaction is standing next to that adult dog knowing that what they invested in the hard months made the difference.
