On-leash aggression towards dogs

Why does my dog bark and lunge at other dogs on leash?

First, rest assured, you are not alone. This behavioral issue is so common that there are volumes of books specifically written about the subject. Dog trainers and behaviorists refer to this issue as “on-leash aggression” or “on-leash reactivity”. That being said, this is a serious issue that needs addressing as soon as possible – the longer you wait, and the more it happens, the harder it is to address. A reactive dog can bite other dogs and even bite dog owners nearby.

What is it?

A dog with on-leash reactivity often gets along marvelously with other dogs when off-leash at the park, or in the yard, or even in home. But the minute you put on a leash and go for a walk, he becomes interested, then agitated at the sight of a dog at a distance. As you get closer, he expresses the frustration by barking, howling, lunging, and even biting. He’s so fired up that calling his name, luring him with food, or even applying leash corrections does nothing.

A fear aggressive / reactive German Shepherd lunges at another dog
A fear aggressive / reactive German Shepherd lunges at another dog

Photo courtesy of Päivi Reijonen (dog trainer and behaviorist) – view the entire set on Flickr: http://www.flickr.com/photos/30096200@N08/sets/72157623555143141/


What causes it?

Every dog is different, and it is difficult to figure out exactly why a specific dog develops this issue. Here are a few common reasons:

The dog never learned to walk loosely on leash, or focus on the handler when called. As a result, the dog is used to pulling around everywhere to investigate everything. The sight of a dog on the sidewalk is a novel distraction at first, so a puller struggles to go meet and sniff that other dog. Naturally, on-leash, and on the sidewalk, your dog doesn’t have the freedom to wander up and sniff every dog. The frustration of being unable to get to that interesting thing, compounded by the physical pain of the collar tension that occurs when pulling towards another dog is highly unpleasant. Soon, the dog associates the sight of another dog with feelings of frustration and pain, and very soon, through simple classical conditioning, the dog sees other dogs on the street as the reason for that feeling and pain. As it happens each and every time they see a dog on leash, the conditioning occurs very quickly.

The dog had learned to be fearful or dislike other dogs. This can occur if a dog has been harassed or attacked by another dog – sometimes it just takes one bad experience to make a dog fearful. This can also occur if a dog was not exposed to a wide variety of other friendly dogs while it was a puppy. In an off-leash setting, the dog has the option to flee. When a dog is on leash, we’ve taken away that option, so all that’s left is freeze, or fight. The on-leash reactive dog is barking and lunging to send the other dog away proactively.

The dog may be ill or injured. Dogs hide injury well, and perfectly well socialized dogs that suddenly start acting aggressively (in any context) may be hurt and vulnerable, and instinctively become more defensive. Make sure your dog is fully vetted to check for illness or injury.


What does not cause it:

Unfortunately, many “experts” are extremely misinformed about this and most other behavioral issues. Here are the most common and incorrect explanations they provide:

  • The dog is “dominant” and wants to fight every other dog.
  • Dogs have been selectively bred over many generations to avoid conflict – a species that is genetically predisposed to fighting tends to make itself extinct. Also, if the dog was a natural born fighter, he wouldn’t be an angel at the off leash dog park.
  • The dog doesn’t respect you as the “leader” or “alpha” or whatever and therefore is protecting you.
  • There is a behavioral issue called “resource guarding” where dogs guard their owners, but it is far more rare and typically occurs on or off-leash.
  • On-leash reactive dogs can be extremely well trained in obedience, and do everything their handler asks, and still lunge and bark.
  • You are not calm and assertive.
  • You could be totally oblivious to the fact there’s a dog approaching (and therefore relaxed) and the leash-reactive dog would still bark and lunge if they see the other dog first.


What training techniques should we avoid?

If you are advised to do any of the following, run far, far away from that trainer:

  • Leash corrections
    • The dog already fears and dislikes other dogs. Causing additional pain and discomfort whenever he sees another dog only compounds the feelings of frustration, fear, and hatred. The correction may suppress the behaviour  but the emotional attitude the dog has continues to slide into deeper frustration and hatred of dogs on leash. The dog has also not learned any desirable behaviour in its place (such as look at the handler).
  • Spray bottles or citronella collars
    • Many dogs fear spray bottles or citronella collars, so these “softer” aversives should not be used for the same reason. Conversely, many dogs do not care about getting water in the face, rendering them useless. In both cases, the dog has learned nothing.
  • Physical violence (yelling, hitting, poking, tapping, kicking, alpha-rolling, etc.)
    • You may suppress the behaviour (probably not) but you have also put yourself at severe risk of being bitten.
    • A dog learns that humans are dangerous, and hands are dangerous – you are creating a fear-biting dog.

What should you do about it?

Any behaviour issue that puts dogs and people at risk of injury is serious and is not something you should address on your own. This work requires you to have both knowledge of classical conditioning, operant conditioning, and practical work to manage your dog and deliver food rewards all while walking your dog on leash. Get the help of a professional dog trainer or behaviourist that prescribes the following:

  • Manage the environment – do not allow your dog to rehearse the barking and lunging. This means maintaining distance from other dogs while on leash as you train.
  • Change the dog’s emotional attitude towards other dogs while on leash – This is best accomplished by feeding your dog high value food (cheese, hot dogs, steak, chicken) each and every time he sees a dog while on leash.
  • Focus on safety – a head halter, or in extreme cases, a basket muzzle, ensures that you, your dog, and other owners and dogs are safe while you do the work.
  • Train an incompatible behavior – If you train the dog to look at your face and lock on when a dog approaches, it now has something to do other than bark and lunge.


Compare and Contrast: Good Training vs Bad Training

The first video has Dr. Sophia Yin (www.askdryin.com) using a combination of operant conditioning and classical conditioning to teach a leash-reactive dog to tolerate and then eventually like other dogs. You know this dog is happy because of his body language.

The second video from a certain TV program shows the use of severe leash corrections as a punishment to suppress behavior. In this case, the aggressive dog looks at another dog – the person kicks the dog (2:56), triggering the dog to bite, and then proceeds to choke the dog till it nearly suffocates. The person is bitten and dogs subjected to this punishment will suffer neck, spinal, tracheal, and ocular damage. If the owners tried this they would likely require hundreds of stitches.





Get Help!

We recorded a 90 minute live webinar called Leash Reactivity 101, where we go into much more depth. If you’d like to get access to it, click here and fill out the form and we’ll email you a link to view it.


Also, we are proud to offer our Behaviour Modification services to anyone, anywhere in the world via videoconference. Since March 2020 and the Covid-19 Pandemic, we have been seeing clients via videoconference and we’re been able to help people and their dogs regardless of where they’re located.  So even if you’re not based in Toronto, Canada, contact us to see if we can help you…

Click here to learn more about our Behaviour Modification services.

32 Replies to “On-leash aggression towards dogs”

  1. This is a great technique that my trainer here in Ottawa had recommended. Though now my dog does great when she is on leash, when she gets off leash she lunges after dogs on leash (she has always been fine with off leash). Would you have tips for how to change that? Everything she knows goes out the window as soon as she sees a dog on leash, no recall, no looking back at me, nothing. Perhaps I could try working with her in a smaller area where it’s easier to get her attention?

  2. In general, it is irresponsible of a dog trainer to provide advice on aggression without working directly with the client in person, so I would recommend you please consult your trainer in Ottawa. If you need a recommendation, look up the trainers at Carolark in Ottawa for help.

    In general, the question I would ask is why is your dog off leash, if she lunges at dogs on leash? It sounds like some fundamental things need to be looked at. If she runs off without permission and lunges at dogs, she should not be off leash until more training and behaviour modification has been implemented.

  3. Thanks for this information! I have a 10-year old male neutered Beagle. He is an inside dog and is best friends with my two other dogs. He walks beautifully on a slack leash, even ignoring flocks of geese. However, as soon as he sees a dog in the distance he tenses, pulls, and begins barking uncontrollably and it becomes almost impossible to refocus him. I could never tell if the cause of this was fear, confusion, or aggression (he’s a lamb at home- no food aggression, no toy guarding, nothing). I clicker-trained “look” at home, rewarding him for sitting and looking at my face. This mostly worked today at the park- he saw two dogs and began to get tense, but I was able to keep him looking (rewarding him with pieces of chicken) two different times as they passed. I noticed that the second time it was a little harder to keep him form focusing on them, but he didn’t bark once, which is a major improvement. What is an average time frame to where a dog goes from reactive to relaxed using the method you showed in the video? Weeks or months? Also would a dog like this benefit from going to dog daycare and socializing or would that be a frightening experience? I was thinking maybe that if he found out that strange dogs are OK at dog daycare, maybe seeing one at the park is not such a big deal? Thanks again for the tips!

    1. Hi Sharon, I am glad you found the tips helpful. It is inappropriate to give advice regarding dogs that are displaying aggressive behaviour without establishing a client relationship, so really you should be working directly with a dog trainer/behaviour consultant who understands how to use positive reinforcement/systematic desensitization and counter conditioning to help you. If you are not in our area, feel free to email and we can try to send you a recommendation.

  4. This was a reassuring article to read. I’ve been searching for ways to correct this behaviour in my puppy and will try the techniques shown in the first video. However, I do have a question maybe you can answer? I have a 5 month old rescue pup (have had him for a month) and he does exactly this. I socialize him by taking him to an off-leash park (in Berlin), and there he’s fine and does play with other dogs(there his recall is actually quite good, and I’m going to continue reinforcing that). When he’s on-leash on the sidewalk, he will lie down if he sees another dog approach and have them approach him if there’s time and space. In this scenario he usually does fine but does get excited as the other dog passes at times. But if there isn’t a chance for him to lie down he just reacts by barking and pulling towards the other dog. In times where other people panic and there’s too much around, is it okay to pick him up (because he does stop barking if I do)? I don’t want to create any bad habits by doing so, and also that there are so many dogs in Berlin that it would be impossible to pick him up every time something like this happens. Thanks in advance!

  5. Will be trying this out, my boy has got a lot worse recently and is made worse when the path is narrow. He’s fine with 90% of dogs off lead but on lead I just don’t know when he’s going to react anymore :-/. Will try food but he has been protective of food with animals since his brother died recently so i’m not sure if this will make him worse :-/

  6. Hi, I have recently got a 4 year old Black German Shepberd female.She is so well trained and obedient that I suspect she may well have been trained professional. She is a complete joy to work with , its like she knows what to do before I have even asked her.One BIG problem i’ve discovered is when on leash she will lunge , growl and snap at ANY Dog she passes ! I have been distracting her whilst they pass and she quickly stops.
    However I was out walking in local woods , she was off leash and playing fetch, darting off and bringing it right back repeatedly to drop at my feet.
    Next thing I saw was an off leash Springer happily heading in our direction with his owner walking behind.My girl took off at high speed and bascially body slammed into the Springer, knocked it over and came running back when I called her. I leashed her immediately , took away the ball , checked the other dog was ok. I didnt acknowledge her other than saying No ! Playtime was over and we walked home.I can’t allow this to happen again, why is she attacking any dog without even being close to them on or off leash ?

    1. Did you ever find help for your dog? I also have a black shepherd who is 2, he is a total sweetheart until he sees another person/animal then barks aggressively.

  7. I have a 3 year old rescue that is a husky/? mix. She was a stray found with her pups in a garbage dump. She has severe dog aggression while on leash and at home when being introduced to other dogs. She settles down at home but has managed to pull free of her harness while walking. I live in Nova Scotia and I know you cannot offer advice but I would like to know what trainer in the area can help her. Do you know of anyone here? Thanks.

  8. We have two dogs, a 3 year old daschund/chin mix and our newer addition a now 8 month old Saint Bernard. Our smaller dog has always been a bit reactive on a leash, we did do a lot of training with her she listens well and will stop the first time we ask her stop. Problem is that now our 100lbs Saint bernard is doing the exact same thing and despite ongoing training definitely has a much more stubborness to her and fixates more on the other dogs. It is harder to distract her. The lunging is the worst part because so many people want to come up to her with their dog and to pet her and she will just lunge and bark agressively (although I really dont feel its aggression as much as it just sounds aggressive) And it really freaks people out. I am embaraased to admit that we did for a while do the leash correction, but now once we see a dog approach we will each take a dog in separate directiions away from approaching dog. We put our dogs in sit and make them hold a sit position by trying to keep them focused on us and not the dog. It takes a bit of the fun out of being able to approach other dog owners and chat. I would like to know if this is a learned behavior? Did our saint benard pick up this lunging and barking from our smaller dog. And are the feeding off eachother? Should i be walking them separately while i work with them on this, although I am worried if I do that than the.minute I walk them together again the behaviors will start over… Do you habe any advice degarding this?

    1. My advice when working on fear and aggression issues is to get off the Internet and please look for a local dog trainer/behaviour consultant that uses positive reinforcement.

    2. Hello,

      I am having the same problem with my own Saint Bernard. He is very friendly and does great off leash, however barks and lunges when he sees other dogs when on walks. It upsets me because people are scared of him now, when in reality he is a super sweet dog! Did you end up finding a solution to your problem?

  9. I have a 2 year old Dane (rescue) who reacts to other dogs, bikes and big trucks while on leash. We have been doing training and she does great at home but when we are out for walks, won’t listen and I can’t find any food reward that will get her focus back on me…any suggestions?

    1. My advice when working on fear and aggression issues is to get off the Internet and please look for a local dog trainer/behaviour consultant that uses positive reinforcement.

  10. I rescued a shar pei just over a year ago , he was a really bad puller but doesn’t seem as bad know , what hasn’t got better is on leash lunging and barking at every dog we see …highly embarrassing and this week bit me in the thigh while restraining him from lunging and trying to attack another dog . I can understand frustration at always being on leash , I’ve seen exactly what he does off it is attack . Though I take him to my mothers who has a terrier and gradually I’ve been able to take his leash and collar of and even walk them together . Some pointers would be good

  11. I have a 6 month old male German shepherd that we’ve had since he was 9 weeks. We started socializing him right away taking him everywhere we could; dog parks, walks, friends who have dogs. He went to puppy classes at Petsmart for even more socialization. Recently he started showing on leash aggression. Lunging at people, dogs, cars, golf carts, barking wildly. He loves dogs at the dog park and our house and has always been good with people but once he’s on a leash he becomes a maniac. I have no clue what started it as we never used to pull him away from dogs on the leash, until he started going crazy. In fact we encouraged him to approach dogs,m ( with the owners consent of course).
    He is starting his second puppy classes with a behaviour trainer but that doesn’t start for another month and I get nervous walking him on the street now.
    I really am confused to what started this behaviour

    1. Wondering if you were ever able to resolve this? We have a puppy who is the same age and breed, with the exact same issues

  12. I have a new german shepherd. She is 6 months old. Barks at everything very aggressively. Pulls the leash. I have no control of her outside house. Inside house and yard she’s perfect.

  13. Some visitors commented that they found our suggestion of “Get off the Internet” to be rude. The advice is get off the Internet and look for local help! I am glad you found this article. Now, the next step is… find local help! OK, use the Internet to find local help if you need, but you will need some hands on assistance to help you. Examples of credentials to look for include Karen Pryor Academy Certified Training Partners, or trainers who have their CPDT-KA certification, or possibly graduates of other good programs such as The Academy for Dog Trainers (Jean Donaldson) or Pat Miller Certified Trainers.

    1. i found it very abrupt also. it’s quite insulting in fact.
      most of us possibly have local help. i am in the middle of a training program right now but it seems sensible to learn as much as you can whilst waiting for your next local training session. also before it’s done we are not sure how successful the local training will be and we want to get on with something that works. if we are boring you with our questions then just don’t reply and people will look elsewhere. people are just desperate for some extra help that’s all.

  14. Hi we have a 6 year old blue staffordshire terrier gor him when he was 2 (rescue) and he is seriously bad on leash (can’t have him off) when he sees a dog off leash he happily toddles on past but as soon as he sees a dog on leash he pulls and lunges and in most cases bites me I have countless bruises and bites all over my legs he also does this at home he can be happily sat on the couch watching tv and getting cuddles and then all of a sudden go crazy and rip my socks off and bite my feet ….on another occasion when he was chained in the garden sun bathing my partners mum went down to bring him in and he lunged at her face luckily didnt harm her …..is there a reason for this behaviour and any home training tips please

  15. I have just rescued a staffy who’s four and she’s never been off the lead apart from a secure area.

    She walks fine with my mum’s dog but the guy at the rescue centre doesn’t know how she gets on with other dogs or children (as she was teased by them).

    She growls and lunges towards other dogs.

    I have only had her two days but want to sort this out.

    Any ideas ??

  16. I think if I had the money and the time I would get my dog properly leash trained so that he would respond to cues even in the face of other dogs being around but in the meantime I don’t have that luxury so it’s a corrective chain harness and a muzzle while we’re on walks. At home he’s such a good boy and listens well but every time there’s another dog around he’s a monster and he starts to snap at his walking partner reactively. The strange thing is he walks slack on the leash all other times and only some dogs will he lunge and get tense about not all.

  17. Thanks for the good article. I just adopted a dog who is leash aggressive and I’ve found a local trainer.

  18. We have a 1 year old puppy. He is very friendly towards people but with dogs, he becomes very aggressive, barking, trying to bite, and he does not stop. This occurs when he is on a leash and we have not tried when he is off-leash as we fear he will bite or attack other dogs. When he is on leash and sees a dog, he will tug, lunge, bark, and sometimes deflect his aggression to his handlers, biting wherever he can on them. We have attempted several sessions with a dog trainer who has focused on leash training and dog avoidance, that being said, he still becomes extremely aggressive despite all the leash training. Is there anything or techniques that you can possibly recommend to better introduce our puppy to other dogs?

  19. We have a 1 year old puppy. He is very friendly towards people but with dogs, he becomes very aggressive, barking, trying to bite, and he does not stop. This occurs when he is on a leash and we have not tried when he is off-leash as we fear he will bite or attack other dogs. When he is on leash and sees a dog, he will tug, lunge, bark, and sometimes deflect his aggression to his handlers, biting wherever he can on them. We have attempted several sessions with a dog trainer who has focused on leash training and dog avoidance, that being said, he still becomes extremely aggressive despite all the leash training. Is there anything or techniques that you can possibly recommend to better introduce our puppy to other dogs?

    *edit, used the incorrect email in the reply function.

  20. We have a 6 yr old Yorkie mix rescued about 3 yrs ago. He is delightful, very friendly in home and outside for the most part and generally at walks as well. We’ve trained him with “look at me” and “good boy” and he usually responds well. However he randomly decides to be aggressive with other dogs – both off and on leash. He happily goes up with his tail wagging then suddenly decides to grisl and snarl (he doesn’t bite). He also decides he doesn’t like certain dogs we see regularly, usually large, dark coloured dogs. I try to be pro-active and get him focused on me when I see we’re passing a dog on a walk. Sometimes it works, sometimes it doesn’t?? Other times he totally disregards all dogs both on and off leash. It is typically worse when he’s on leash. Mainly I give other dogs a wide berth if I can so he can enjoy our walks. I’m going to watch your Leash Agression webinar for some tips (Once the pandemic is over, I do intend to find an in-person trainer in downtown Toronto).

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