Dog-Dog Aggression On Leash (Reactivity)

Why Dogs Bark and Lunge on Leash

Does your dog whine, bark, growl, or lunge when they see another dog while they’re on their leash? This unpleasant but common behavioral problem in dogs can be caused by barrier frustration. From nature’s side, dogs are strongly motivated to greet one another, and on leash, they can’t always do that.

Barrier frustration is intense frustration on the dog’s part at the inability to express normal canine body language and/or interact with other dogs. The restrictive barrier is the leash in this case, but can also be something like a window, fence, or gate. In essence, the dog’s frustration has amplified to a point where they can’t help their reaction.

On-Leash Aggression vs. Off-Leash Aggression

Though leash aggression can look vicious, it disappears when the leash comes off and the dog meets other dogs off leash. If your dog shows aggression toward other dogs when meeting off leash, then that is serious aggression. See Dog-Dog Aggression: Off Leash.

What You Can Do About It

Stay calm. Use a happy tone when approaching on-leash dogs—stay calm, but aware. Be prepared to move away quickly if needed (duck behind a car or cross the street) from the other dog. Keep the leash loose if possible. If you seem tense or uneasy and tighten the leash, your dog will sense your uneasiness and may respond by pulling and barking.

Use a humane training collar. A head halter such as the Gentle Leader or Halti, or a front buckle harness such as an easy walk harness makes on-leash management much easier and doesn’t hurt your dog. Choke, pinch, and shock collars, on the other hand, are designed punishment tools causing pain and discomfort. Your dog might stop barking because it hurts, but the pain won’t decrease their frustration. In fact, keep in mind that the association with pain can cause or worsen the aggression.

Play the “Find it” game. Have a handful of yummy treats, tell your dog, “find it,” and throw a treat in front of him. Continue to say, “find it,” and throw treats until you are safely past the other dog. This exercise distracts your dog from other dogs by keeping him focused on treats. Instead of staring at the other dog, your dog’s eyes will be searching for treats. Eventually your dog will associate the sight of other dogs with yummy food.

Feed your dog at night. Make it a habit to only feed your dog after you’re inside for the evening. That way, you’ll always go on leashed walks with a slightly hungry dog who is much more motivated to focus on you and the goodies in your treat bag.

Take a class. We offer reward-based behavior modification classes, called Reactive Rover, for dogs that are leash reactive. Sign up on our website.


  • If you haven’t done so already, spay or neuter your dog.
  • If your dog is friendly and social off leash, provide them with daily off-leash play with other dogs. Make it a point to let them off his leash to play as a reward for sitting first. This can greatly reduce on-leash frustration.

If you can’t take a class and your own efforts aren’t successful, contact SF SPCA’s board-certified veterinary behavior specialist. Don’t live in the Bay Area? Search locally for a veterinary behavior specialist (Dip ACVB), a Certified Applied Animal Behaviorist (CAAB or ACAAB), or a Certified Professional Dog Trainer (CPDT).

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