5 Reasons Why a Dog Attacks another Dog for No Reason

Aggressive Dog

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.

  • Dogs may do a “play bow” before they play with one another. The bow consists of the dogs lowering their front legs and chest, and straightening their back legs.
  • Your dogs may reveal their teeth but they aren’t growling aggressively as they do so. They may lightly nip at the other dog’s ears or nose.
  • Dogs will take turn playing different roles when they play with one another. For example, one dog may first chase the other before they switch roles.

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 on MyPetChild.com is for informational purpose only. It is not intended to be a substitute for professional veterinarian advice, diagnosis, or treatment. Always seek the advice of your veterinarian when in doubt.


  1. Steve Riches January 6, 2021 at 5:28 pm

    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

    1. Sarah Godwin February 12, 2021 at 1:26 pm

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

  2. Rosemarie May 24, 2021 at 11:40 pm

    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?

  3. Brenda Wilkin July 21, 2021 at 5:23 am

    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

  4. Jim Bennett August 30, 2021 at 5:23 am

    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.

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