Dog Attacks Another Dog Unprovoked and for No Reason – Top 5 Reasons

First off, there is always a reason for a dog attacking another dog or another person. It may just seem like there isn’t, especially when your dog rarely ever shows a worrying level of aggression. Here are some situations that may get your dogs to “attack” one another.

1. Your Dog is being Playful
Dogs, specifically puppies, may look like they are attacking another dog, when in reality, they are just trying to be playful. There are certain clues that may help you determine whether your dog is fighting or playing.

2. Same-Sex Aggression
Same-sex aggression may occur among dogs, especially if they have a lower tolerance of sharing the same resource with other same-sex dogs. One research study found that female dogs were more likely to get into an aggressive situation due to same-sex aggression.

3. Your Dog was Provoked
Your dog may have finally snapped after being provoked by the other dog for a prolonged period of time. This kind of situation may occur between puppies and older dogs. The puppy could have been trying to get the older dog’s attention for play time but the older dog might not have wanted any part of it.

Dogs may also feel provoked if they feel like the other dog is trespassing his territory. This is worrying because the dogs in your household should feel as if they are one pack, and not as individuals. We recommend consulting a professional trainer if you feel the fights are caused by territorial issues.

4. Your Dog is Jealous
When dogs share the same household, they’ll eventually figure out who is above the other in terms of their pack status. If the owner starts to give the lesser-status dog more attention than the dominant dog, it may cause the dominant dog to get jealous and attack the lower-status dog.

5. Traumatic Experience
This is more likely with dogs that have been rescued or adopted. Dogs may suddenly become overly aggressive against other dogs if they recall a past experience that involved a lot of neglect and abuse (e.g. dog was rescued from a dog fighting ring).

We strongly recommend you visit a professional trainer or a pet behaviorist if the inter-dog aggression continues to be a problem between your dogs. Dog aggression doesn’t just pose a threat for the dogs involved. It also poses a threat to other dogs and humans that interact with the aggressive dogs.

You should also identify and eliminate all the stressors that are causing your dog to become aggressive. For example, if the dogs are fighting due to the confusion over their pack status then it is important for the dog owner to respect the dominant/submissive status set between the dogs.

Disclaimer: The content is not intended to be a substitute for professional veterinarian advice, diagnosis, or treatment. Always seek the advice of a veterinarian when in doubt.


  • Steve Riches | 06/01/2021

    Our rescue dog that we have had for 3 years now has taken to aggressively running at, barking at and has now attacked a smaller dog. She also did this once last year and we put it down to the fact that she may have been frightened by something and was on the lead.
    We literally were commenting on how she had calmed down a lot over the course of the years we have had her and how she had become more affectionate and loving.
    She is our 3rd rescue dog – the first was a full blooded male Alsatian I rescued from the USA , the 2nd was an Alsatian cross who was wonderful and now the 3rd is again an Alsatian cross Collie from Romania. This is a total of 30 years of rescue dogs, so we are not ammatures at this.
    As with all three of them I /we have resolved most of the dogs concerns and issues and this is the only dog which has got us worried – I am a mature person and have been around animals all of my life and do not understand this behaviour from this dog.
    She is 4 years and and a half years old – we have had her since she was 14 months old.
    Can you offer any advise as to what might be the trigger for this behaviour ?
    Thank you in advance

  • Sarah Godwin | 12/02/2021

    Hi Steve, have you had any help yet regarding this issue ?

  • Rosemarie | 24/05/2021

    We have a 15 year old male cocker and a 8 1/2 year old female. The female has been sweet to him up to 2 weeks ago. For no apparent reason, she attacked him twice. She claimed alfa status from the very beginning. The male does not fight back. He is old and sickly. What do I do?

  • Brenda Wilkin | 21/07/2021

    my son had a female , 4 years old, de sexed recently, and since then she has been attacking his 5 month old puppy.
    The older dog was re homed to him after being used as a breeding dog, but he was assured that she had also been a family pet. She has a very sweet nature, and he got the puppy after getting the older dog and they got along extremely well. Eating and sleeping together, and the older dog seemed to mother the pup.
    After the older dog being de sexed, she started being aggressive toward the puppy almost immediately.
    The older dog is a Bull Terrier, 4 years of age. The pup is a staffy cross and also has a beautiful nature. We are firstly worried that the older dog may harm the Puppy when not being watched, and also that it may make the puppy start to show aggression and develop fear of other dogs in general.
    We would appreciate any suggestions on reasons and solutions to this problem

  • Jim Bennett | 30/08/2021

    We have a 2 year old golden who has been socialized since early days. She has had two incidents of attack without backing off. The first occurred while playing with balls at a dog park with dogs she knew and had socialized with many times. She attacked the dog who got the ball first and clung on after the ball was dropped. Our vet said it was overstimulation (take the balls out of play) and she was starting a false pregnancy. He said this would cause excessive resource guarding. This was around 17 months old. Fast forward to a situation with another golden where they had played together daily at each other’s houses, and due to a gate in the fence they could come and go as they pleased most of the day. While playing last night the other dog yelped (it was at the other house and family was right there) but our dog did not back off this time and the other owner got scratched separating them. Is there anything we can do and should we be worried about her with other dogs she has been good with and/or children (which she has always been good with)? BTW, other dog was fine, no marks or anything.

  • Barbara | 30/10/2021

    I have a 6 mo golden that weighs 60 lbs.we were leash walking yesterday when a large and small dog approached us on leash. They all pulled toward each other when the large black dog attacked my 6 mo old leaving a cut over his eye and pinning him to the ground. Why is my question? All are well behaved other times.

  • Melia Franck | 15/11/2021

    I have an altered male dog. We frequent our local dog park. He plays very well with all the dogs normally but this one day we had just walked in and he made a straight line to a male dog that wasn’t even aware he was coming and attacked him. Very sweet dog. We went back to the park on several other occasions. Then one day when we went back that same dog was there and my dog ran straight to it again and attacked without provocation. He singled this dog out twice. We haven’t gone back since. Why would my dog behave this way?

  • James Pajak | 28/11/2021

    As I was just just about to go into my garden with my cocker spaniel I said hello to another dog walker he had Alsatian.suddenly without any reason attacked my dog nearly bit me and bit his owner on the arm I was told he never done that before

  • Robbin J French | 18/04/2022

    what happen with the attacked another dog.. were there in tickets involved?

  • Norma Leverenz | 11/09/2022

    I have a rescue male pit mix dog and have had him for 5 years. I also have a female pit that I got at birth and she is 4 years. We go to my boyfriend’s home where he has a German Shepherd and they have been together for 3 yrs on and off and play well always. This last weekend, he watched all of the dogs while I was out of town (which he has done before and vise versa) but my male , while unprovoked, attacked the Shepherd and took her to the ground and had her by the neck. Paul had to pull him off by his back legs and he tried a second time but was stopped. The Shepherd stayed away from him for the next 2 days and he acted like nothing happened. Don’t know what I should do to make sure he does not do it again.

  • Melanie | 06/12/2023

    We have same issues as Steve above. Can you help?

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