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Mean on Leash? Why otherwise friendly dogs may behave aggressively when on-leash.


© 2012, Belvoir Media Group, LLC.

No portion of this article may be reproduced without permission of the copyright holder. Reprinted with permission from , Belvoir Media Group, LLC..

Reprinted with permission, Belvoir Media Group, LLC.
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If you hang around with other dog owners, you've no doubt heard the same comment I have, over and over again: "My dog is fine with other dogs when he's off-leash; he's only dog-aggressive when his leash is on." You may have even said it yourself.

The reason it's an often-heard comment is that it's a common behavior: A lot of dogs who are fine with other dogs when left to their own devices become aggressive if they are leashed when they meet other dogs.

We know that aggression is caused by stress. (See "A New Threshold," WDJ October 2010.) Clearly, there is something about being on a leash that a lot of dogs find stressful enough that it prompts aggressive behavior. There are several reasons for this. Let's take a look at each of them.


Picture in your mind two dogs meeting and greeting, off-leash. They engage in a social dance - advancing, retreating, moving around each other, sniffing various body parts, giving body language signals intended to keep the interaction civil. Sometimes the movements are slow; sometimes they are quick. If one dog is cautious or fearful of the other, he can retreat as he wishes, using social distance to keep himself safe.

Now picture those same two dogs meeting on-leash. The dance is stilted, inhibited by the restraint of the leash. One dog tries to circle the other, and the leash tangles around his legs. The cautious dog would like to retreat to safety, but knows the leash restricts his movement, and elects to act out his second option to increase distance - a growl and a snap to signal to the other dog to move away - who cannot, because he is leashed. The fight is on.

In the future, the cautious dog will offer a growl and snap before he's close enough for the other dog to make contact. The best defense is a good offense. Alarmed, owners move away from each other, and the fearful dog's aggression is reinforced by the increased distance. Behaviors that are reinforced repeat and increase, and the cautious dog's aggression escalates as he realizes that it's a successful behavior strategy for him - it keeps other scary dogs away. You now have a leash-aggressive dog. Absent the leash, he still chooses to move away from the other dog - his first behavior choice.

The tense, tall, forward posture of the Labrador - caused by his pulling on the ineffective choke chain - looks very similar to an aggressive posture, and could cause the other dog to be defensive.


This is the dog who would love to visit with other dogs, on- or off-leash. In fact, you have reinforced his "I wanna go see the other dog!" behavior by frequently allowing him to greet other dogs on-leash, being careful to keep the leash loose, as your instructor showed you in class, to avoid having the leash interfere with the dogs' normal social interaction. However, sometimes owners of approaching dogs give a clear indication that they don't want to allow their dogs to greet yours. You politely comply, restraining your dog with his leash to hold him back.Your dog, who suffers from low impulse control and low tolerance for frustration, becomes highly aroused when his desire to greet the other dogs is thwarted. His frustration and arousal turn into aggression, and your dog is labeled as "reactive." Absent the leash, he would have happily greeted other dogs without any frustration or aggression.

Again, the impression that is given to other dogs (and nervous owners of other dogs) by the posture created by the dog's frustrated pulling on the leash is one of aggression, whether the dog is aggressive (yet) or not.


Stories abound of dogs who are ferocious if the owner is in the room, or holding the leash, yet turn into pussycats when the owner leaves or hands the leash off to someone else. One possibility is that the dog is protecting his owner. Another more likely one is that the owner's presence gives a fearful dog enough confidence to act aggressively, but the dog shuts down when the owner leaves. Yet a third and perhaps most likely explanation, is that the owner is stressed in anticipation of the dog's behavior in the proximity of other dogs, as well as other coming events - such as obedience ring competition. The stress of the human is an added stressor for the dog who is well aware of his owner's emotional distress (they are masters at reading human body language, remember?) and that's enough to put him over his aggression threshold.

As much as possible, keep your leash (and body language) loose. Keep breathing, and reward your dog for breathing, too!


If you ever made the mistake of punishing your dog for inappropriate behavior toward other dogs on-leash, you may have given him a negative association between the leash and the presence of other dogs. Verbal corrections, a jerk on the leash or, horrors, a zap from a shock collar, are all stressors that your dog might now associate with the presence of another dog when he's on his leash. That added stress can cause him to be aggressive when he otherwise might not have been.Perhaps he was attacked by another dog when he was on his leash. Attacks can create very strong negative associations; you will often see a dog who is on-leash-aggressive toward a particular breed, type, or color of dog that reminds him of a prior aggressor.


Sometimes introductions seem to be going well until one owner turns to leave, and pulls on the leash to get her dog to come along. Suddenly a fight breaks out for no apparent reason other than the leash tightening.

If things were already a bit tense between the dogs, the tightening of the leash can easily trigger an aggressive outburst. For one thing - it's a stressor. Imagine if you were engaged in conversation with someone, and someone grabbed your arm - or worse, your shirt collar - and tried to pull you away. Annoying, yes? Well, annoying equals stress - perhaps enough stress to trigger an outburst.

For another, picture two dogs standing nose-to-nose, with some tension between them. Now envision the dog's body language when his owner pulls back on the leash. The opposition reflex (scientifically named "thigmotaxis") causes him to lean forward, tighten his muscles and stand a little taller - all of which mimic an assertive, perhaps aggressive body posture in a dog. If the annoyance-stress isn't enough to trigger aggression in that dog, his offensive body language is likely to trigger an aggressive response from the other dog. You can find an excellent example of this phenomenon on this YouTube video:


Each of the causes for on-leash aggression has its own remedy. Some require preventative action - proactive steps that reduce the likelihood of future aggression. Others respond well to intervention in the actual moment of potential aggression. They all require that you keep a cool head when you identify possible trouble spots.


I make it a pretty strict rule not to introduce dogs while still holding leashes. My dog-to-dog introduction routine involves letting the dogs see each other from a distance and, if all appears copacetic as the dogs near each other, dropping leashes and letting the dogs interact normally, without human interference. If the meeting unravels, we can grab leashes and separate the dogs without risking a close encounter with flashing teeth. If all goes well, however, we remove leashes after a moment or two of greeting, and allow the dogs to play freely.


My rule about "no greetings on-leash" works well to proactively prevent leash-restraint frustration. Because my dogs aren't in the habit of routinely greeting other dogs on-leash, they don't develop that expectation, and therefore don't become frustrated when it doesn't happen. I teach my dogs that when they are on leash, they are with me, and their job is ip to pay attention to me. Only when and if I drop the leash and give them the "Go play!" cue do they expect to interact with an approaching dog.

For this reason, we do not teach an on-leash greeting exercise in our good manners classes (greeting humans, yes; greeting dogs, no). We aim to convince our students of the value of the no-greeting rule from Day One of their first class, in part to decrease the potential for on-leash frustration-aggression. (If your class instructor wants you to participate in an on-leash dog-to-dog greeting exercise, feel free to politely decline.)


This one might be more about you than it is about your dog. I generally counsel my clients not to leave their dogs in the hands of strangers - even veterinarians. Without you there to protect your dog, some may resort to inappropriate use of force to coerce your dog into cooperating. Forcible restraint is likely to exacerbate your dog's stress and resulting aggression. Your veterinarian may be able to get the job done, but your dog's behavior could escalate and worsen with each subsequent encounter.

You need a two-pronged approach to this behavior - modification protocols for your dog and you. Meditation, yoga, biofeedback, and other self-calming procedures are useful to train and remind yourself to stay calm during interactions that might otherwise cause your dog to react to your stress with aggression. "Square breathing" is one simple technique you can use to calm yourself and reduce your own stress. You can also teach your dog to breathe, and then ask him to breathe on cue - reducing his stress - and giving you something to think about and do, which also reduces your stress. (See "Calm, Slow Breathing," opposite page.)


The greater the intensity of the prior negative association, the harder you will have to work to overcome it.

If your dog has perceived that the presence of another dog causes pain or discomfort to his neck - from the shock of an electronic collar, the pinch of a prong collar, or even the choking of a flat collar - start by changing the equipment.

Then implement a counterconditioning and desensitization program to other dogs. Dog at a distance makes chicken happen (the other dog needs to be far enough away ("sub-threshold") so as not to elicit an aggressive response to your dog). Let him look at the other dog; feed him chicken. Let him look again; feed chicken. Look - feed. Look - feed. Over and over, until, when he sees another dog his brain thinks "Chicken!" - and he no longer stresses over the presence of the other dog.

Then gradually decrease the distance between your dog and the other dog, and increase intensity of the stimulus in other ways: multiple dogs, more movement from the dogs, direct eye contact with the other dogs, offset walking (walking in the same direction but not right next to each other); parallel walking (next to each other, dogs on the outside humans on the inside); offset approaches, and finally, direct approaches.

If your dog was actually attacked by another dog on one or more occasions, the negative association may be even more intense, and modification even more of a challenge. If the mere presence of another dog is a very strong stressor for your dog, you may want to seek the assistance of a behavior professional for your modification program, and a veterinary behavior professional, for a discussion of behavior modification medication.

Pratice calm breathing with your dog at home, and as you and your dog gain competence, practice in gradually more distracting environments.


The solution for this is absurdly simple: just teach your dog that the tightening of the leash reliably predicts wonderful stuff. You need your dog, on-leash, and a large supply of his favorite treat, cut into pea-size pieces. Now pull gently on his leash - and feed him a treat. Do this multiple times, until a tug on the leash prompts your dog to turn happily to you in anticipation of a goodie. Then increase the pressure on the leash, and the duration of the pressure. Next, practice the "leash pressure equals treat" game in the presence of increasing distractions, and finally in the presence of other dogs.

Identify and address the specific cause of your dog's on-leash aggression; manage his on-leash behavior to prevent the frustration, arousal, stress, and fear that are the root causes of his undesirable behavior; give him new associations with the presence of other dogs; and keep him safe from inappropriate social interactions (canine and human), and he will be well-positioned to succeed.

Pat Miller, CBCC-KA, CPDT-KA, CDBC, is WDJ's Training Editor. She lives in F'airplay,Maryland, site of her Peaceable Paws training center, where she offers dog training classes and courses for trainers. Pat is also author of many books on positive training, including her newest, Do Over Dogs: Give Your Dog a Second Chance at a First-Class Life. See page 24 for more information.

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