Why is my dog aggressive to other dogs?

One of the most common behaviour problems I get called in to help with is a dog which is being aggressive to other dogs that it sees when out on the walk. So most owners are keen to know why their dog is aggressive to other dogs.

Commonly thought reasons for aggressive behaviour…

  • Lack of socialising/puppy training
  • A bad experience in the past (was attacked by another dog)
  • Owner is nervous around other dogs.
  • Dog is fearful of other dogs
  • “It’s a rescue”

There can be some truth in these thoughts, but in most cases, the reason an owner gives tell that their dog is aggressive to other dogs is just a really small piece of the pie.


To understand why a dog really is aggressive to other dogs, we need to understand their perspective of the situation and their perspective of us.

The dog’s perspective of the walk.

Imagine for a moment that you are in the military. You are on a tour in Afghanistan. You are relaxing in the base camp, when someone else from your squadron comes in and tells you to get ready; you’re going out on patrol in the next few minutes.

This is how a dog can view the outside world. Your house and garden are your territory. They are where your dog feels safest. Beyond your house and garden lies potential danger. Your dog sees the outside world as:

  1. A further extension of your territory which is constantly being invaded by others.
  2. The territory of another pack, who might not be too happy to find you there.  OR
  3. A no-man’s land which everyone is trying to claim as their own.

In the wild, territory battles get messy. Wolves will kill other wolves to gain more land. More land means more resources, and survival of the pack, so it’s serious. Your dog’s instinct tells them that going outside is serious. They won’t have had the same experiences as their ancestors, but that doesn’t stop them from potentially assuming the worst.

“But my dog gets really excited about going for a walk…”

An adrenalin rush is what you are seeing when your dog realises a walk is about to happy. Much as I would experience at the idea of leaving the base camp in Afghanistan. I very much doubt I would be excited/happy about the prospect, although I do know some people who are keen on that sort of adrenalin rush; they are few and far between.

So how does this affect them being aggressive to other dogs?

  • If your dog thinks that another dog is on your territory, they may feel compelled to defend their territory and fight/warn the other dog off.
  • If your dog thinks that you are on the other dog’s territory then it will anticipate hostility and could be aggressive as a mean of defense.
  • If your dog considers you to be on no man’s land, then it could do either of the above scenarios.

The level to which your dog’s behaviour goes will depend on its personality. Some dogs will go for aggression straight away because they feel they have no other choice, whereas for others it is an absolute last resort.

The dog’s perspective of us.

Often when I give this explanation people will tell me that they realise that’s how their dog is feeling, so they go around the walk, reassuring them that everything is okay. This can have very mixed results. Some dogs will think you are scared too, and that’s what you are saying. Others will think “what do you know?”

Think back to the Afghanistan example. If you were the commanding officer and you saw your squadron getting ready to leave, you would as quickly as possible get ready to go with them, so that you were there to take charge of things and make any important decisions that needed making. Now imagine that members of your squadron weren’t taking things very seriously. They weren’t doing what you were trying to get them to do, or they kept hindering your progress or talking to you while you were trying to make important decisions…. Would that make you feel more stressed, or less?

In this example, your dog is the commanding officer, and you are the unruly squadron (I know it feels like it’s the other way round – we are just looking at your dog’s perspective right now).

This is the key to preventing behaviour which is aggressive to other dogs…

We are actually the biggest factor in all dog behaviour problems. Without our involvement, dogs would settle their battles on their own. Much like cats do. They would only go places that they felt it was okay to do so. They’d avoid certain dogs, join forces with others, and they would generally be much more relaxed.

Since we introduced “walking the dog” a few decades ago, we have made things much more complicated for our beloved pets. Admittedly there are safety reasons that we can’t let them go out on their own anymore (though cat’s are still let out), and laws about having dogs out on their own (again, different rules apply to cats…) which are what they are. If we want to get walking them right, the first thing we need to address is our relationship with them. They need utter clarity that they are not in charge. If you do not have this around the house, you have no chance of having control on a walk.

When you can show your dog that they can trust you to be in charge of the pack, then they can slowly learn that the walk isn’t a problem, and other dogs aren’t a problem. From the safety of knowing that you are going to take responsibility and deal with any situations if it came to the crunch.  Rather than thinking that you need dog training, realise it’s leadership training from a dog’s perspective that you need!


2 thoughts on “Why is my dog aggressive to other dogs?

  1. My dog is a year old was socialised straight away but the last few weeks is turning a little aggressive towards dogs his known since pup and meets nearly every day?

    1. Hi Heather, It sounds like your dog is coming of age, and is starting to think that he needs to prove himself a little around these other dogs as he may feel that are a slight threat to either your well being, or his status when you are out and about. How does it usually happen? Is it every dog?

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