Interdog Aggression: Why Dogs Fight With Other Dogs

Anyone who has ever witnessed the horrifying experience of interdog aggression and seeing their dog attacking another dog knows all too well the terror of the moment. Interdog aggression is displayed towards other dogs and not toward people. Even though the dog displaying interdog aggression may be acting out of a sense of territorial protection, the owners of the “offender” are plagued with many conflicting emotions as a result of their dog’s “crime.” On one hand you, the dog owner, feel angry at your dog for attacking the other dog that you want to punish your dog. However, on the other hand, you might feel sad or guilty because you realize your dog was only trying to protect you. At all times, it is a nightmare to live through for both you and the dogs involved.

interdog aggression


Stop Interdog Aggression:

* Your dog growls at other dogs, nearby. Growling indicates your dog’s desire to attack.

* Instead of eating a treat immediately upon receiving it, your dog is overly possessive of the treat and hides it or stands guard over the treat so that other dogs or pets won’t take it away. This is also a form of antagonism that your dog is displaying toward your other pets which is another way of saying: your dog is picking a fight.

* What started out as usual playing among your dog and another dog, turns into a hostile fight or growling match. If your dog is not aggressive, they will submit and not growl back.

Risk Factors Associated With Interdog Aggression:

* Fear of being attacked by the other dog, though there may be no indication of aggression made by the other dog.

* Insecurity. Your dog’s insecurity is different than a human’s insecurity: If your dog doesn’t spend his days burning off energy hunting and chasing vermin in the yard or critters in the forest and doesn’t have a good foundation of obedience training and socialization, (s)he doesn’t have the self-confidence necessary to know how to have a balanced relationship with another dog, or how to act when one on one with another animal. This lack of experience causes to insecurity which turns into aggression. Note: allowing your dog to hunt in the woods or in your yard is not suggested to solve insecurity. A professional dog trainer or professionally-advised handling tips must be used to strengthen your dog’s sense of self so (s)he won’t have to resort to violence against every dog encountered.

* Your dog’s natural sense of being territorial. Protecting your home and property might not be behavior that you want to change. If your dog is aggressive towards other dogs that come near your home but is not aggressive when away from your home, you’ll need to make sure that your yard is well-fenced. Also, for some flock guardian breeds, this behavior is encouraged.

* Suffering from previous owner’s over-socialization with older dogs, as a puppy. If you have a rescue dog that is displaying strong dog aggression, chances are high your dog was not socialized properly. (S)he has learned to defend themselves with violent means. If you are an owner of a rescue dog, you probably don’t need to be told that you should start your dog on a “Nothing In Life Is Free” program and begin obedience training exercises so that your dog develops a vocabulary and relationship with you, that will allow you to communicate with your dog that fighting with other dogs is not tolerated.

* Some breeds are more prone to this form of aggression. For some dogs, there may be a genetic component to the aggression.

* Dogs that are often bred to fight are certainly more susceptible to fighting. Dogs like Pit Bulls, Bulldogs, Bull Terriers, Akitas and Shar peis come from a long line of fighters. They have the thrill of the fight in their blood and though they are not natural hunters or have not been abused as puppies, they may (but not always) have a natural instinct to fight with other dogs.

Signs Of Aggression Between Dogs

* While walking on a leash, your dog sees another dog and makes every attempt to wiggle out of his leash in order to attack another dog.

* When you open your front door, your dog tries desperately to run out to attack another dog.

* At the dog park, your dog starts out playing with another dog but begins to fight physically with that other dog over a toy, bone or area of the park.

Stop Interdog Aggression

* Choose a leash and a training collar. Learn the right technique to teach your dog to walk on a loose leash. This can be learned in less than an hour, and for some dogs… in less than 10 minutes. If your dog is not pulling on the leash, there is a 90% chance he won’t be aggressive toward other dogs.

* Hold the leash by putting your thumb through the loop, and then folding the leash in half and close your fist around both strands of the leash. Do not simply grasp the ring of your dog’s leash to hold on to him/her. This is the number one way a dog gets lost. If your dog is prone to running, bring your other hand up under your first hand (two hands, together) which gives you firmer control of the leash.

* Break in the use of a muzzle on your dog, before you encounter another dog.

Note: never force your dog to wear the muzzle for longer than five or ten minutes the first several times. A muzzle can be a stressful experience for your dog.

The first five or six uses of the muzzle, only keep it on your dog for ten minutes and keep your dog inside. Reward them with a treat upon removing the muzzle. After the sixth use of the muzzle, venture outside with your leashed dog and only keep him or her out for 20 minutes maximum. Increase accordingly.

Let me reiterate that interdog aggression (more commonly known as just “dog aggression”) is distinct from “handler aggression” in that the dog is aggressive toward other dogs, and this behavior may be completely devoid of handler aggression.  In other words: Sometimes we’ll see dogs that are perfectly fine around adults, children, babies … even other types of animals.  But when it comes to interactions with other dogs, you’ll see the aggression come out.


Interdog Aggression – What Are The Warning Signs?

In all cases, there will be physical signs– although sometimes subtle– of the aggression, before the dog acts.  This may include:

  1. Stiff and rigid body language.
  2. Pulling the mouth closed tightly.
  3. The dog may lock his gaze with the other dog.
  4. Curling of the upper lip.
  5. Lowering the head (in a stalking/hunting-like position)
  6. Dominant body language or seeking to be physically in a higher position than the other dog.
  7. Hackles up
  8. Lips curled tightly against the teeth, and showing of the teeth.

Types of Interdog Aggression

Interdog aggression can be broken down into the same main subcategories that every other type of dog aggression can be categorized in, namely:

  • Dominant aggression
  • Fear aggression or defensive aggression
  • Territorial aggression
  • Protective aggression (usually of puppies)
  • Pain response aggression

Of course, there are others, but most will fit within one of the above mentioned categories.

Eva writes: “You are so right, Adam! My German Shepherd experienced the same thing and at 2 years of age he became interdog aggressive. I have had 11 “Dog Trainers” and the last one finally told me to have the dog focus on me when other dogs approach. He is doing ok with only one or two other dogs while focusing but when 4 or more dogs come at him he loses it and attacks. I can only walk him with a shock color and, when I see other dogs approaching, ( tough to see them when they come from behind), have to put a muzzle on. I have to be on a constant lookout for other dogs and had a very stressful life with him for the past 6 years, he is now 8.
Sincerely, Eva”

Catherine adds: “I don’t know if you’ll see this reply, but my dog is a great example of your description of how interdog aggression gets started. Maya is a german shepherd/blue heeler mix and was very friendly as a pup. When she was about 9 mos. old and we were out for a walk, a neighbor’s dogs came after us. This happened a few times that summer, then again the next summer. Although they never bit her or us (my husband and I carried pepper spray and a baton to protect ourselves), we could see it dawning on her that “a good offense is the best defense.”

By the middle of Maya’s 2nd summer (when she was almost 2 years old) — and after talking to these neighbors and then finally reporting them to the dog control officer — the neighbors finally got their dogs under control. However, Maya had become a snarling, aggressive dog that was very difficult to control, even with other quiet, friendly dogs…and it had carried over to people.

It has taken me 3+ years of working with her with a prong collar and an e-collar so that she is no longer challenging and showing aggression to the neighborhood dogs. Sometimes we even walk with them and their owners. She is also better with people but still fearful. So, we still have a ways to go — and it’s all because we were attacked by those dogs when she was young.

The funny thing is, when I take her other places, Maya shows little interest in other dogs and is never aggressive towards them. In fact, her behavior in obedience classes as well as a class for becoming a therapy dog was better than anything I ever hoped for — even when other dogs misbehaved or were aggressive, she was fine. We now visit the skilled care section of a nursing home as a registered therapy dog team, and she is fine with the residents in wheelchairs, walkers, and other equipment…as well as the elderly miniature poodle that has the run of the place. She also seems to enjoy children. However, she’s still afraid of standing adults who can get around on their own. I continue to work with her on that fear, taking her to town or other situations with people for socialization at least once a week. — Catherine Seebald”

Philis writes, “Interesting article about interdog agression vis a vis socialization.How about an instance where a 4 year german shepherd, neutered and pack leader of 3 females and 1 male with whom he has been close to and best buddies unto the male turned 2 (he is intact) and the shepherd has now attacked him severely three times and the dog who was attacked is now living temporarily with me and my 2 females. Philis Raskind

Working with a dog that displays interdog aggression can be dangerous.  If you’re at all afraid of your dog, then by all means contact a professional dog trainer.   You might also want to take a look at my book, “Secrets of a Professional Dog Trainer!” and all of the accompanying bonuses that can help you get inside your dog’s head and teach him/her to stop the interdog aggression, as soon as possible.