Understanding developmental stages and behavior shifts in dogs
Just like humans, dogs don’t stay the same from puppyhood through adulthood. As they mature, you might notice changes in your dog’s energy levels, confidence, sociability, and even reactivity. These shifts are often misunderstood, but they’re actually a natural part of canine development.
Let’s break down the science behind these changes and how to help your dog navigate them with confidence.
1. Adolescence Isn’t Just for Humans
Many dog owners are surprised when their sweet, social puppy starts to act out around 6 to 18 months of age. But just like teenagers, dogs go through adolescence, a period marked by hormonal shifts, brain development, and social re-evaluation.
📚 What the science says:
A 2020 study published in Biology Letters found that adolescent dogs (around 8 months old) exhibited more conflict with their caregivers and were less responsive to cues compared to when they were younger. This mirrors what we see in teenage humans, who are biologically wired to test boundaries as they transition into adulthood.
🔍 Real-life example:
Your calm, responsive Shepherd mix suddenly starts barking at noises outside and acting more alert on walks. This doesn’t mean they’re becoming aggressive or that training didn’t work. It’s often a sign they’re entering a new developmental stage where their awareness is expanding. Stay consistent with structure and support, and they’ll regain emotional balance as they mature.
2. Behavior Can Regress Before It Gets Better
Sometimes, it feels like your dog “forgets” their training. They might start pulling on leash again, barking more, or even becoming more sensitive to sounds or movement. This isn’t a step backward. It’s a sign that their brain is reprocessing and re-prioritizing information.
🧠 Neurological development:
The canine brain continues to develop into early adulthood. Just like toddlers who suddenly become clingy or emotional, dogs may have “regression periods” as their cognitive and emotional systems mature.
👣 Example from daily life:
A dog who was once crate trained might suddenly resist the crate at 9 months old. Instead of scrapping the crate, revisit foundational training and build it back with short, positive sessions.
3. Social Preferences Shift with Age
Your dog’s early social behavior isn’t always a preview of their adult personality. Many dogs become more selective with other dogs as they mature, and that’s normal.
🐾 Research shows:
Socialization windows (usually under 16 weeks old) are critical, but dogs still go through secondary fear periods and social threshold changes later in life. According to the American Veterinary Society of Animal Behavior, a dog’s sociability is influenced not just by exposure but also by genetics and environmental factors.
🐕 What this can look like:
Your friendly Golden Retriever who loved every dog at the park now growls or avoids high-energy puppies. It’s not aggression. It’s emotional maturity and setting boundaries. Think of it like an adult who outgrows the party scene.
4. Hormones Play a Big Role
If your dog is intact (not spayed or neutered), hormones can significantly affect behavior. Increased marking, mounting, and roaming tendencies can emerge or intensify in adolescence and early adulthood.
🌡️ Science-backed observation:
Hormonal surges can influence stress levels, territorial behavior, and even how your dog reacts to other animals. Some dogs become more assertive or reactive during this stage.
🧬 What you can do:
Understanding that hormonal behavior is temporary doesn’t mean letting it slide. Training, movement, and mental stimulation are key. In some cases, your vet may discuss whether sterilization could be appropriate based on behavior and health.
5. Your Dog’s Needs Evolve
A calm puppy might become a high-drive adolescent. An independent breed may become more attached as they grow older. Age, experience, and environment all shape behavior over time.
💡 Example:
A dog who once didn’t care about being left alone may develop separation-related issues after a major life change like moving homes, welcoming a baby, or returning to the office after remote work.
📈 Your job as an owner:
Adapt your training and lifestyle to support your dog’s current needs, not just who they were as a puppy. Adult dogs still need structure, stimulation, and guidance, even if they “know better.”
Final Thoughts: Behavior Changes Are Normal
Dog behavior is fluid. It reflects age, maturity, life experiences, and even our own behavior as owners. Instead of getting frustrated when your dog’s personality or behavior shifts, lean into it. Recognize it as an opportunity to strengthen your bond and continue their growth.
At Monument City Dog, we specialize in helping dogs of all ages learn how to navigate the world calmly and confidently. Whether you’re dealing with a wild adolescent or an adult dog going through new challenges, we’re here to help guide the way.