Why does my dog lunge and bark on leash? (Leash Reactivity Explained)

Have you ever wanted to know why your dog goes crazy at the end of the leash when they see a dog or person? Or why your dog loves to chase cars? In this post, we’ll explore the most common causes for your dog’s reactive behavior like barking and lunging on walks.


But first of all, let’s bust some myths:


Your dog is NOT reactive because…
  • You are a bad leader
  • Your have the wrong “energy”
  • You are not authoritative enough
  • You need to show them barking and lunging is “wrong”


Here are some more helpful ways to look at your dog’s reactivity:

  • Barking and lunging are natural responses for the reasons we’ll get into in a moment.
  • To reduce your dog’s reactive behaviors, we need to understand your dog’s motivation.
    • Why is the dog reacting, from their perspective? In other words, What is the function of the behavior?


Does reactivity mean my dog is aggressive?

Not necessarily. True “aggression” means the dog is experiencing a strong negative emotion – commonly fear, worry, or discomfort; and the dog is using aggression to keep a perceived threat at bay. Sometimes it’s true – dogs do bark and lunge on leash when they’re afraid of a trigger. But this is not always the case!


The tricky thing is this – 


There is not always a visual difference between reactivity based in fear, and reactivity that is not.


Since we can’t tell by looking at the dog, how are we supposed to know what the cause is?


The question to ask is this…

What happens when you take the leash out of the picture? 


In other words, how does your dog behave when let off-leash around their trigger? Does the barking and lunging fade away completely? Does your dog approach the trigger in a friendly manner when given the chance? Or do they keep their distance? If your dog’s trigger is other dogs, then how does your dog like to play with other dogs off-leash, or do they prefer to be left alone?


Note: Different triggers can have different “causes” for the reactivity. For example, your dog might react fearfully to strangers, and excitedly to squirrels. So it’s important to evaluate each of your dog’s triggers individually to discover the root cause of their reaction.


Causes of Leash Reactivity

When it comes to explaining leash reactivity, most reactive dogs fall into one of two camps – barrier frustration or fear. Let’s look at barrier frustration first.


Barrier Frustration

Barrier Frustrated dogs are not “aggressive” in the true sense of the word – rather, they want the trigger to come closer! But the fact that they are held back by the leash leads to barking and lunging out of frustration that they can’t access what they want. Another way to think of Barrier Frustrated leash-lungers is that they are interested, rather than avoidant.


Usually this happens when the dog is motivated by social or prey drives. For example, frustration is usually the case with dogs lunging at things that move, like cars, bikes, or small critters. (Most dogs aren’t afraid of squirrels – they just find it fun to chase them.) 


Here are more examples of how to tell if your dog might be reacting out of interest/frustration:

  • Dog reacts to dogs on leash, but enjoys playing with other dogs, visits dog park/daycare and plays well
  • Dog reacts to humans on leahs, but is friendly towards human visitors to the home, or when allowed to get close to a person on a walk
  • Dog reacts to moving objects or vehicles (cars, bikes, skateboarders, etc.)
  • Dog reacts to prey animals (squirrels, rabbits, birds, cats, etc.)



Reactivity that is based out of fear is often the case when the trigger is a social being, like reactions towards dogs and people. This includes when a dog only reacts to a subset or more specific category of triggers i.e. children or men. Fear is also often the cause if novelty or a sudden change in the environment is what sets your dog off (I.e. someone standing up who was sitting, or a person appearing around a corner suddenly). 


Here are some behaviors you might see from dogs that react out of fear:

  • Dog has a history of aggressive or fearful behavior towards dogs or people in off-leash situations
  • Dog shies away from triggers off-leash (hides from other dogs at the dog park, hides from people or won’t let strangers pet them)
  • Dog reacts to “strange” objects, like statues, lawn decorations, or other unusual visual “pictures” that your dog doesn’t recognize


Once I understand my dog’s reactivity, then what?

Understanding why your dog barks and lunges at certain triggers will inform what you do next to manage and train your dog. 


For example, if you determine that your dog is fearful of other dogs, then you want to make sure you make a management plan that will protect your dog from encountering other dogs in ways that frighten them.


On the other hand, if your dog is a frustrated barker, then part of your strategy could be to visit the dog park more often to let your dog fill up on social time with other dogs. Then, the trigger of seeing another dog becomes less compelling and your dog’s reactions will be less intense. 


Different causes of reactivity may be better suited to different training approaches too. Training for fearful dogs needs to put the emotional state of the dog first and foremost. Whereas with frustrated dogs, you have a little more leeway with which training approach you choose.


For help training your reactive dog, contact a qualified positive reinforcement trainer. 

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Mara Clare Van Valzah, CTC, PNWI

Mara Clare Van Valzah, CTC, PNWI

Dog Trainer & Behavior Consultant

I founded Collaborative Canines to help dog owners to better understand, communicate with, and coexist with their pets. Here, I share my dog training stories, tips, and tricks with you and other dog lovers all over the world. 

Dog problems?
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I help dog owners just like you find better lives with their dogs every day. If you live near Anaheim, CA, and your pup could use some guidance, contact me!

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