3 Reasons Your Dog Might Be Reactive

3 Reasons Your Dog Might Be Reactive:

1. Missed or Limited Socialisation

One of the most common reasons dogs develop reactivity is missed or delayed socialisation. And if this sounds familiar—please don’t blame yourself.

Puppies go through a critical fear period between 8–16 weeks, where every experience helps shape their behaviour. This is the ideal time for gentle exposure to new people, dogs, and environments. But sometimes, life doesn’t go to plan: vaccinations, illness, or timing can limit these early experiences.

Even in adult dogs, lack of regular, positive exposure to other dogs can make unfamiliar interactions feel overwhelming, leading to reactive behaviour.

2. Past Trauma or Negative Experiences

Reactivity can also stem from fear caused by a traumatic event. If a puppy is frightened or overwhelmed by another dog during their fear period, they may develop long-term anxiety around other dogs.

Likewise, if your dog has been attacked or had a bad experience, no matter how old they were, it can create lasting fear and defensive behaviour. Their reactivity is often a way of saying, “I don’t want that to happen again.”

3. Genetics and Breed Tendencies

Your dog’s breed and genetic background also matter. Some breeds, especially guarding types, may be naturally more wary of unfamiliar people or dogs.

Genetics can influence temperament just as much as environment. If your dog’s parents were fearful, anxious, or reactive, those traits may have been passed down. That’s why researching breeders and parent dogs is so important, but even then, some traits are simply part of who your dog is.

Reactivity is complex and multi-layered. But it’s not a reflection of a “bad dog” or a “bad owner.”

Have a question about reactivity? Feel free to get in touch

Emma, Elmtree Dogs (BSc, MSc Animal Behaviour & Training)