My Dog Attacked Another Dog Unprovoked. Why & How To Stop It

If you’ve recently been shocked that your ordinarily well-behaved dog attacked another dog unprovoked, you’re likely filled with questions and concerns.

Canine aggression can manifest unexpectedly, leaving pet owners grappling with worry, guilt, and confusion.

I’ve faced this issue myself (more than once).

It’s a tough topic, but with patience, understanding, and the right strategies, you can help your canine companion navigate through these behavioral challenges.

So stick with us and let’s discover how to turn this stressful situation into a stepping stone towards a healthier, happier dog-human relationship.


Common Reasons Behind Inter-dog Aggression:

  • Illness and injury
  • Fear
  • Possession aggression
  • Dominance
  • Frustration
  • Jealousy


My Dog Attacked Another Dog Unprovoked — How I Solved the Aggression Problem

Not so long ago, my dog attacked another dog unprovoked. Out of the blue. For no apparent reason… or so it seemed to me.

We were having a casual, relaxing stroll like we always do, when all of a sudden, my pooch started snarling and lounging at the other dog out of nowhere.

He went from a perfectly calm and happy mood to a state of total frenzy in seconds!

My pup not only growled at his opponent but also jumped at him and even attempted to bite!

Luckily, I composed myself quickly after the initial shock and separated my dog from the other one.

Otherwise, I would probably have had a lawsuit on my hands by now.

The strangest thing was that the canine in question was a neighbor’s terrier that my dog got along with just fine up until that point.

So as soon as I got home, I called my dog’s trainer and asked for advice. Here is everything I learned about why my dog attacked another dog unprovoked.


The Common Reasons Behind Inter-Dog Aggression

Talking to the puppy trainer was an eye-opener. He made sure to explain everything in detail, and he really covered all the bases.

The incident between my dog and his new nemesis happened once more after that. But thanks to our trainer, I knew exactly how to react the second time around.

The first thing that my trainer pointed out was that dogs don’t necessarily like all other dogs.

And even when they do get along with another pup, sometimes they get into a fight and lash out.

That could be why my dog attacked another dog unprovoked. But there could be more than meets the eye.

If there are repeated inter-dog aggression, it could be because of a more serious underlying issue.

Namely, our dogs could be having some physical or psychological problems that we are unaware of.

So if we think there is something going on with our pup that is making it act out, here is what it could be:

  • Illness and injury
  • Fear
  • Possession aggression
  • Dominance
  • Frustration
  • Jealousy


Illness and Injury

Dogs are aggressive when they are suffering. Although this isn’t the most prevalent cause of dog aggression, my dog trainer warned me that it is the first one to be ruled out.

It may have seemed that my dog attacked another dog unprovoked because he was in pain, and I didn’t know it.

I took my pooch to the vet the same day to verify he was as fit as a fiddle.

The vet was particularly instructive — she explained that many illnesses don’t show apparent symptoms in the initial stages.

But they cause our pups pain nevertheless — and make them more irritable in turn. That is why they are more likely to lash out toward other dogs and humans, too.


Some of the most painful and hidden conditions in canines are:

  • Hyperthyroidism
  • Injuries causing acute pain
  • Cancer
  • Epilepsy
  • Arthritis
  • Ear infections
  • Tooth issues
  • Encephalitis
  • Brain tumors


The puppy doctor did a thorough physical examination and the necessary blood work on my pup, and fortunately, he was the spitting image of health!



Dogs can feel fear just as much as we can. And just like us, they have the “fight or flight” defense mechanism deeply rooted in their genetic makeup.

When a dog feels scared, it would most probably run away, but if it is on a leash, it succumbs to the alternative protection method — fight!

Dogs that feel threatened by another dog but are tied up, realize that they are in an inferior position. So they give to snarling, snapping at the air, or even biting.

They do it to show that they are, in fact, formidable opponents and to try to scare their threat away.

That is particularly common in traumatized dogs that were scuffed by other canines before.

If you adopted a rescue dog that used to be in dogfighting rings or was abused in another way, it could be the reason for its aggression.

In that case, you would need to consult a canine behaviorist to help your dog overcome this issue.


Possession Aggression

Possession aggression, or resource guarding, is the second most common cause of inter-dog violence.

Dogs don’t only guard their owners, but they are highly possessive about their belongings.

It could be that your dog is guarding his territory, or he could be keeping other dogs from his bowl, food, or toys.

Dogs will show varying degrees of possession for different objects. For instance, your dog may love its chew toys but won’t mind when another pup sniffs them.

On the other hand, it may go berserk when the other dog approaches its most coveted spot on the couch!

Although the dog in question didn’t intend to lounge on the couch and was just passing by if your dog sees that as menacing, it will act according to its instincts.



All canines feel the need to be dominant. It is not a personality trait but the expected behavior in the species.

When an unfamiliar dog enters our pup’s territory, its supremacy is at stake, and it will need to reaffirm its position as the alpha dog in the hood.

Here is the behavior you can expect in such situations:

  • Snarling
  • Excessively loud and deep barking
  • Snapping
  • Raised fur
  • Chasing
  • Fighting


It should go without saying that we ought to prevent the situation from escalating. It is alright to allow our pup to show how tough it is by yapping and growling.

However, if things seem to be going out of hand and we notice that the dogs could get into an actual fight and bite each other, we need to move our dog away.



Dogs can feel frustrated if their basic needs are not met.

Depending on the breed, they will require a specific amount of physical activity, and that includes spending time outside and off-leash.

Also, dogs that are not spayed or neutered feel the urge to mate with other dogs that are within reach.

But most of the time, they just want to play! Dogs that spend a lot of time indoors or by themselves are yearning for company.

Having fun with their human families will usually suffice, but sometimes, they could feel frustrated because they cannot play with the dog in the yard across the street.

A dog that doesn’t get out enough may feel overstimulated at the sight of another dog, and its behavior may spiral out of control.

That is particularly common if your dog finally gets close to the dog from across the road that it’s been eager to get to for so long.

However, frustration and pent-up energy may lead to redirected aggression, which can be dangerous for you.

If your dog gets into a clinch with another dog, they could hurt you when you try to break them up. When dogs are violent, their cortisol and adrenaline levels are through the roof.

When you intervene, they could attack you without intending to, so it’s best to stop the conflict from the get-go.

The best way to prevent aggression caused by frustration is not to expose your dog to its familiar stressors.

If you know that seeing the other dog triggers such behavior, take your dog out when the other pup is indoors.

If both dogs spend a lot of time in their yards, set up opaque panels along your fence to keep the other pup out of your pooch’s sight.



My dog attacked another dog unprovoked because he was jealous. Having ruled out all other options, our trainer concluded that my pup was being overly protective of me.

So when the familiar neighborhood terrier approached me a little too close for my dog’s liking, he snapped at him to chase him away.

And the chances are that I am to blame for that jealous streak in my dog’s temperament.

Although I went to great lengths to train and housebreak him properly, I didn’t do enough to socialize him when he was still a puppy.

My dog is used to people coming to our house and to hanging out with other dogs at the dog park.

What he isn’t comfortable with is seeing me engage with other dogs, because he is my only pet.

That is undoubtedly something to mull over if you are thinking about getting a new puppy.

I have since booked sessions with an animal behaviorist whom my trainer warmly recommended, and my pooch has been doing amazingly well!


Final Thoughts

When my dog attacked another dog unprovoked, I didn’t know much about what could be causing his aggression.

It turns out, canine violence is never without a cause, although it may sometimes seem so to us.

Hopefully, my story was useful to you if you are going through a similar situation with your pooch.

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