My dog Rex is a rescue dog, and an aggressive one. He was known at his former shelter for breaking out of his cage and fighting other animals. He will see another dog at 500 ft. away and start "dancing" back and forth, yelping and jumping on two feet, eager to charge and snap.

But this is not always the case. While he was still at the shelter and I was volunteering there, I successfully—with the help of other shelter employees—"packed him up" with three dogs: another pit bull that was 100+ lbs and also aggressive; a young hound puppy that was less than 1 yr. old; and a pit bull mix about 3 years old. The last one was the only dog Rex would actually play with: they would jump up and "hug" (the way boxers play), and run around the shelter's yard together. Unfortunately, they got in a very bad fight right before I adopted my pup, otherwise I would've taken them both!

Even since I've adopted him, I've taken Rex on morning "pack walks" with other dogs, all of whom are well-adjusted and usually off-leash. Two trainers lead these walks, and my dog—though he was required to wear a muzzle and leash—eventually warmed up to the other "regular" dogs, walking alongside them extremely well. He was even beginning to playfully charge one of the trainer's dogs. We've since stopped these hikes because Rex has heartworm and can't be too active.

Now the reason I've wanted to socialize Rex was because I live in a neighborhood with lots of dogs. Also a lot of idiots live here, walking there dogs off-leash, even on the sidewalks of our streets! Note: I know this is very illegal, but it's still something I have to deal with. But even ignoring these idiots, almost everyone in my family owns a dog!

OK, finally to the question:

What is the best way to introduce my dog-aggressive Rex to other dogs?

I've tried several ways, all with varying bits of success: walking the dogs far apart, and gradually getting them closer and closer; walking Rex with a muzzle until he "settles down"; even letting Rex jump and lunge at the end of the leash until he realized he couldn't get the other dog. Again, all have worked more or less, but it is still true that:

  • Rex brutally injured his only "friend" when the other dog snapped at Rex;
  • He was never walked at those morning pack walks without the muzzle on, so it's not clear if he would've still been aggressive;
  • None of these have reduced Rex's aggression towards "new" dogs.

I'm really looking for a way to best teach Rex to "tolerate" other dogs. I've read several articles and blogs about introducing two dogs, but they never deal with the case of a dog as aggressive as Rex is. Let me stress that it is not my intention to force Rex into potentially very stressful situations. It is just a fact of life that he and I meet many dogs every time we go for a walk. Heck, he loves running in my sister's huge backyard, but even she has two small dogs that need to be locked in the house whenever Rex is over.

Dog's history (from comment by OP) :

@psubsee2003: He was owned by a family who most likely abused him (he has strange scars on most of his body, and his tail is broken). He was found in the basement of that family's house: they had moved out and left him tied to a pole. He was adopted quite quickly after being rescued, by a well-meaning family, who made the fatal mistake of (1) using a shock collar to train this already fearful dog, and (2) applying the shock collar for everything (I'm talking barking, peeing in the house, etc.). He eventually bit everyone in the family and was returned.

  • Do you know Rex's history prior to arriving at the rescue? Commented Oct 9, 2013 at 11:55
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    @PreciousTijesunimi: I mean teach him to tolerate other dogs being around him (not necessarily near him though). I don't really know what you mean by "transfer his agresiveness". I'm not trying to agitate other dogs too!
    – Steve D
    Commented Oct 12, 2013 at 15:29
  • Any clue how old Rex is? And how long it was from when he was left in the basement until he was returned by the adoptive family and how long he was at the shelter before you took him? Commented Oct 12, 2013 at 19:44
  • @psubsee2003: He is roughly 2.5 years old. No one knows how long he was in that basement for. He was rescued a little more than a year ago, and the family adopted him quite quickly (within the first 6 weeks). I will eventually get his shelter file, and know more about the exact dates then.
    – Steve D
    Commented Oct 12, 2013 at 22:07

1 Answer 1


I would really urge you to see a professional dog trainer that you trust, with experience with aggressive dogs, and have him assess your dogs and help you out.

But after reading a bit more detail about your situation here than what you gave in another question on why he lunges at children, I'll take a guess at your dog's previous history, which might go some way towards explaining its current behaviour, and I'll try to give you some pointers as to what you can do to improve the situation.

Dogs tend to avoid conflict at all costs

Dogs, by their very nature as social animals, are very non-confrontational. Because they possess very many very sharp teeth, they have evolved a multitude of warning signals that let other dogs know what they are up to*.

**Which is why cats, which are solitary predators, never let you know before they scratch you. Giving away your intentions is dangerous if every interaction with another member from your species is a potential fight.*

Dogs will look away, lick their lips, turn their heads, pretend to sniff and present the side of their bodies in order to calm other dogs down. If that doesn't work, they start staring you down, raising their heckles, baring their teeth, snarl, growl, bark and snap at you, all in order to get you to chill the heck out. Only if none of these signals work will they start biting, and even then it's usually just a quick nip.

However, many of those behaviours are seen as problem behaviours. Many people with a dog that has associated other dogs and people with bad things happening, and therefore constantly growls, lunges and barks at them, will punish the dog for these behaviours. Unfortunately, the dog will fail to pick up on the reason for being punished in most circumstances. Instead, his association of dogs/people and bad things happening will grow but he will start to suppress one warning signal after another until he goes straight for the bite.

I'm suspecting this is what happened to your dog and, depending on how much this has been trained out of him, he could be quite difficult to rehabilitate. Given his history, he probably isn't safe to be off leash around other dogs at this particular time. The main problem is that, if another dog does anything to upset him, he won't let the other dog know that he's not okay with it but go straight on the attack.

Desensitising your dog to other dogs

Your main technique for dealing with this issue, as with the lunging at children, is desensitisation. Slowly introduce him to other dogs in a manner that he is comfortable with. If that means the other dog has to stay twenty metres away, then so be it. Reward your dog every time he shows interest in another dog (i.e. looks at him) with lots of treats and praise. Be very quick in your reactions, you want to reward him for looking and before he starts deciding whether that dog poses a threat or not. Try to set him up for success as much as possible. Every time you judge his comfort zone wrong, he'll regress far more than the progress he gets from one good association.

If your dog does react badly and starts lunging/barking, try to distract him any way you can but without anything negative, otherwise it'll simply reinforce his bad associations with other dogs. For example, try to get his attention with treats and calling his name in a really exaggerated high pitch, happy voice but only reward him after you've asked him to do something, e.g. sit or watch. If you can't distract him at all, lead him away to a distance he is comfortable with, which will likely be around the corner and out of sight of the other dog.

One thing you can do to let him know that you don't want him to do something is to introduce a no reward marker, i.e. a command that the dog associates with losing out on a reward. This can be a simple "oh, oh" or "oh no" in a disappointed voice, rather than the stern "ah ah!" or "no!" you'd use as a verbal correction. Once you have a no reward marker trained in (see below), you can use it to correct bad behaviour without forming bad associations. It won't be enough to stop him barking at other dogs, but if you're trying to distract him with a sit, and he keeps getting up and turning around, it might just make him more likely to listen to you.

How to teach a no reward marker

In order to train in a no reward marker, you need to set your dog up to fail. This seems opposite to what I've said above, but he will only be failing some of the time.

Ideally, get some treats that your dog loves but that you can eat as well. Cheese cubes or hot dogs work great, assuming you're not vegan or lactose-intolerant. Try and find a situation where you ask your dog to do something and you know he will fail a few times. Training in a new command is a good candidate for this. If your dog is a jumper, stopping him jumping up is even better.

Taking that last example as a case study, with the dog sitting in front of you, hold a treat above your head and slowly lower it down towards the dog. Depending on how jumpy your dog is, only lower the treat a little bit before reaching down to it very quickly and rewarding him. The goal is to judge the distance at which your dog jumps and, normally, to reward it before reaching that threshold. You slowly set that threshold closer and closer to the dog's face, until it won't jump up at all and waits for you to give it the treat.

Now, your typical jumpy dog will break its sit and jump up. In this case, quickly pull the treat back up out of its reach and mark that loss of a reward with an "oh oh". That way, your dog will begin to associate the command with not getting the treat. If that doesn't stop your dog jumping after a handful of tries, eat the treat yourself whenever he jumps up. That way, you really hammer home that that treat is gone!

Be careful though to get the balance right, you don't want to frustrate your dog and lose interest. So for every time it gets it wrong, put the threshold further away from its face to a distance you know it can deal with and repeat the exercise from there a couple of times.

Behavioural Adjustment Training

A similar technique to desensitisation is Behavioural Adjustment Training. The basic idea is to retrain your dog to defuse situations rather than escalate them. For that you put your dog in a situation that he is somewhat uncomfortable with but doesn't react to yet. That is, you get your dog to walk towards another dog (or have the other dog come towards your unmoving dog) to a distance that he notices the other dog but does not lunge or bark at it. If your dog starts to show any sort of calming signal (averting his eyes, sniffing the ground, turning its head, licking its lips), you mark the occasion with a resounding "good boy!" and reward him by removing him from the situation, i.e. walk away with him. Your dog would be much happier if everyone else would just keep their distance, so removing him from an uncomfortable situation can be a powerful motivator for him. For this to work, it is even more important not to "set him off". If he does react to the other dog and lunges at him, help him out and move him away from the dog. Make sure to keep him at a much larger distance the next time, as he'll be more sensitive.

For this to really work, though, you will probably need the help of a professional, as your timing and your reading of dog body language will have to be spot on. For a fantastic introduction to dog body language, have a look for a DVD called "Calming Signals" by Turid Rugaas. There's a five minute intro on YouTube that will give you a sense of how horribly produced it is, but if you love your dog, you will brave the sleep-inducing Norwegian accent and the horrible 90s camcorder look. Because for all the cheesiness and tackiness of the video, it is by far the best video on dog body language I have ever seen.

The human factor

Unfortunately, you might, to some extent, also be part of the problem. Having a reactive dog, it is likely you tense up whenever you see another dog or child in the distance, trying to decide whether they'll come close enough for your dog to react and how you can avoid them. Your dog will pick up on that, whether it is from your body language or because you hold the leash ever so slightly tighter. You being nervous is one more reason for him to keep other dogs as far away from him and you as possible. He will also have learned to associate you being tense with other dogs being around, so he will actively look for them.

If you have a friend you can trust to be able to handle your dog under any circumstances, it would be interesting to see him take your dog for a walk to see whether he reacts the same if you are not around.

Even just being on leash, however, also puts up his stress levels, as he knows his movement is restricted. Unfortunately, having a history of attacking other dogs when off leash, it won't be easily possible to see how much being on and off leash affects his interaction with other dogs.

There's bad news and good news

It will be very difficult and time-consuming to socialise your dog to other dogs, and you can probably never trust him fully around other dogs. But with time and dedication, you can alleviate his behaviour to an extent where you are both comfortable and happy to go on walks and be around other dogs without constantly worrying about what might happen.

  • @SteveD I added a section on Behavioural Adjustment Training. It's similar to desensitisation but slightly different and, more importantly, better suited to your situation, I believe.
    – ThomasH
    Commented Oct 12, 2013 at 20:30
  • Thanks so much for the great answer. What you said about going straight to biting is certainly what Rex does: he rarely barks. However, there have been times where we are out on a walk, and he can hear a dog barking (inside someone's house), but can't see that dog. What he'll do then is whine (like a pup might to go outside), lick his lips, and glance in every direction. I guess I should be rewarding that? Also, just to show you it is possible, here's a picture of a dog a shelter employee and I successfully introduced to Rex: imgur.com/iGbNUQT
    – Steve D
    Commented Oct 12, 2013 at 22:05
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    @SteveD It's great that he exhibits the licking behaviour, but you also don't want to reward him for being afraid in the first place. That's why behavioural adjustment therapy uses the walking away as a reward. It teaches your dog that using a calming signal helps it control the situation. It's different than giving him an actual food reward for the same thing, which would teach him that being afraid is the appropriate response. Since he can't locate the dog in that situation, he might not realise he's walking away. So I would ask him to sit or watch you and treat him for that, then walk away.
    – ThomasH
    Commented Oct 12, 2013 at 22:56
  • Actually, I've noticed he is constantly licking his lips when we are outside.
    – Steve D
    Commented Oct 14, 2013 at 18:12
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    @ThomasH +1 the only thing that I don't like is the heading Dogs tend to avoid conflict at all costs I understand what you're saying, it just looks a bit wrong, given the question about dogs accustomed to fighting. I'd rethink it, Most dogs or Well balanced dogs or Ordinary dogs, because some dogs are spoiling for a fight. What do you think?
    – user6796
    Commented Oct 16, 2013 at 10:53

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