I continue to work with countless distraught clients who are desperate to stop their dog’s reactive behavior on a leash. I get it! When I adopted my 9-year-old Scottish Terrier in 2009, I felt the same isolation, stress and frustration. For two years, we trained diligently and, eventually, reached a point where we could walk past people and dogs with nothing more than a low growl. For us, that was a huge win!
In this post, I aim to educate you on the various factors that contribute to canine reactivity and, more importantly, how you can prevent it through intentional socialization. When I refer to reactivity, I am not talking about an exuberant friendly dog that jumps excitedly with its front paws high off the ground. Instead, I am addressing dogs that exhibit behaviors such as rapid barking, snapping when touched, spinning and lowering their bodies as they frantically approach and retreat.
Understanding these underlying causes, and implementing proper positive socialization techniques, have allowed me to raise my two German Shepherds without any reactivity. This knowledge forms the foundation of my upcoming book, and I am excited to share these insights with you. Let me guide you in transforming your dog’s emotional responses for a calmer, more confident companion!
Genetics
Genetics significantly influence a dog’s nervous system, influencing everything from brain development and neurotransmitter function to behavioral traits and stress responses. Reactivity, which refers to how a dog responds to stimuli can be influenced by positive and negative associations to other dogs, people, noises, or different environments. The following are the key genetic characteristics to consider while managing your dog’s reactive behavior:
Temperament
Just like humans, dogs inherit certain temperament traits from their parents. Some breeds or individual dogs are naturally more sensitive, anxious, or reactive to new situations or stimuli. For example, some dogs might be more prone to being fearful or aggressive based on their genetic makeup.
Breed Predispositions
Certain breeds are more predisposed to reactivity due to their historical roles. Working breeds like Border Collies or Herding dogs may be highly alert, responsive to stimuli, and reactive because they were bred for jobs that required high attention and responsiveness. Other breeds, like terriers, might be more naturally inclined to act protectively or defensively.
Sensory Sensitivity
Genetics can also influence a dog’s sensitivity to sensory stimuli (like sounds, sights, or smells). Some dogs are naturally more reactive to noises or movements due to how their sensory processing works. For example, certain dog breeds are known to be more noise-sensitive, which can trigger a more reactive or anxious response.
Genetic factors control the production of neurotransmitters such as dopamine (affecting motivation and reward), serotonin (regulating mood and anxiety), and GABA (inhibiting overexcitement and promoting calmness). Some dogs inherit a predisposition for imbalances in these chemicals, leading to anxiety or aggression.
Health & Neurological Disorders
Inherited conditions such as pain sensitivity, epilepsy, degenerative myelopathy, and cerebellar ataxia highlight how genetic mutations can impact nervous system function. Genetic testing can help identify predispositions to such disorders, aiding in prevention and early intervention.
Inheriting Behavioral Traits
Fear-based reactivity, like resource guarding and some aggression can be passed down through generations. If a dog’s parents or ancestors exhibited reactive traits, the dog may inherit a similar behavioral predisposition. This doesn’t mean that a reactive dog’s behavior is inevitable, but it can increase the likelihood.
Overall, genetics provides the blueprint for a dog’s nervous system, affecting both physiological processes and behavioral tendencies. However, environmental factors such as exposure, socialization, training and diet also interact with these genetic predispositions to shape a dog’s overall nervous system function.
Improper Socialization
Negative or stressful encounters can create serious long-term behavioral issues in our dogs. Every dog has unique social needs based on their inherent sociability, arousal and resilience. Gradual exposure to different experiences helps us observe and understand their comfort levels before introducing them to social settings. Consider the following reactivity indicators associated with improper socialization:
Respecting Boundaries
If a dog is forced into social situations where its boundaries aren’t respected, it’s likely to become emotional about greetings. For example, a shy puppy that fears being petted by strangers might grow up to lunge or snap as a teenager to keep people away. If early experiences teach the puppy that people won’t listen to its signals of discomfort, such as ears way back, compressed body, peeing, obsessive licking at hands and obvious body curving, it may resort to stronger reactions, like barking or biting, to protect itself when it becomes more confident.
When a dog’s boundaries are repeatedly ignored in social situations, it can develop reactivity due to negative associations with other dogs. For the emotional dog or a dog with poor resilience, this often leads to defensive behaviors like barking, lunging, or snapping to keep other dogs away.
Additionally, learned helplessness can occur if a dog is repeatedly overwhelmed without a way to escape, such as when on a leash. This can make the dog either shut down or react aggressively when faced with similar situations in the future.
Experiences
Dogs are social learners, meaning they develop behaviors based on their experiences. A lack of exposure to different situations with people and dogs can create anxiety and uncertainty in a dog. However, when dogs are repeatedly exposed to uncontrolled social settings, such as off-leash parks or daycare environments with little supervision, they may encounter rough play, bullying, or even aggressive interactions. These scary experiences lead to reactivity for the emotional dog.
From a behavioral science perspective, this can lead to sensitization—where repeated exposure to stressful or negative experiences increases a dog’s reactivity rather than desensitizing them. Instead of learning positive social skills, some dogs learn that social encounters are unpredictable and potentially threatening. When these same dogs are later restrained on a leash, they may react defensively—barking, lunging, and showing aggressive behaviors—because they’ve learned that their best strategy to avoid conflict is to act threatening first.
Classical conditioning and Operant conditioning:
Classical conditioning: Repeated stressful encounters with off-leash dogs teach a dog to fear and distrust other dogs.
Operant conditioning: When barking and lunging make other dogs move away, the dog learns to rely on this behavior for safety.
Trauma
A traumatic event is determined by the dog, not us. When dogs experience trauma, whether they’re naturally active or passive, they can develop strong emotions that result in seen behavior changes. Extreme passive dogs with low social confidence, may never gain the self confidence to truly express themselves, yet, their anxiety will increase over time. Dogs with strong social confidence will become defensive or reactive as their safety is intrinsically necessary.
Quality matters just as much as the socialization itself. Controlled, positive experiences build confidence, while chaotic or negative encounters lead to long-term behavioral issues. This is apparent in non social dogs:
Non Social Dogs
Some dogs simply do don’t want to socialize with strangers. Forcing them into unwanted interactions can increase reactivity. A shy puppy that avoids approaching strangers, yet is repeatedly being petted by strangers, may grow into a teenager that lunges or snaps to keep people away. If early experiences teach the puppy that its signals are ignored, it may escalate to barking or biting for self-protection.
When a dog’s personal space is repeatedly invaded without choice, it can lead to aggression or defensive behaviors. For example, if a young dog is frequently made to meet unfamiliar dogs on a leash, where escape or natural body language signals are restricted, it may start reacting aggressively to prevent unwanted encounters. This can create a cycle of reactivity, as the dog anticipates stressful situations and responds preemptively with barking, lunging, or other defensive behaviors.
Prevention
Exposure
To prevent reactivity, dogs need gradual exposure to social interactions in controlled settings. Structured introductions help them build positive associations, develop confidence, and learn appropriate social skills without becoming overwhelmed or defensive. Chaotic environments, like crowded dog parks or uncontrolled daycare settings, can do more harm than good, especially for sensitive dogs.
An important part of early exposure is allowing a dog to approach and retreat at their own pace, especially when interacting with other dogs. If a young dog is rushed into these interactions, it will cause stress, which leads to big emotions and reactivity if not fully resolved.
Observing and understanding your dogs behavior to identify early signs of hesitation, stiffness or stress signals, is essential to slow any socialization situations. If you are unsure, always stick with exposing your dog at a safe distance and avoid engaging with the stimuli until you see your dog is calm and comfortable.
What if your dog repeatedly shows his teeth at approaching dog? Should you punish this? NO! Your dog is expressing his desire to avoid conflict by telling the approaching dog to “go away”. I recommend you do not take this dog to any off leash settings where unfamiliar dogs can freely enter your dogs space.
If on a leash and a dog comes to close, quickly ask the owner to call their dog away, step toward the approaching dog to shield your dog or toss a treat behind the approaching dog then make your exit. You can also teach your dog to circle around you and enter between your legs. This can be taught as a “cover” and will make your dog feel safer in situations that are not planned.
Consider prioritizing quality over quantity in your socialization efforts, to build positive associations and important social skills that will benefit your dog throughout his life.
For another perspective, read my previous Blog: Exposure vs Socialization
Watch this short clip, to better understand When to Let Dogs Greet.
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