How To Handle Interdog Aggression

  • SumoMe

Interdog aggression is a very common problem that I am asked to help with.  I am speaking specifically about dogs that live in the same home, not the dog aggressive dog that wants to go after every other dog he sees who does not share the same address.  I have known people with multiple dogs that are never allowed to be around each.  This one’s in the garage, that one’s in the bedroom, and the other one is outside.  They all rotate places/positions through out the day, but they are never in the same place at the same time.  What a miserable way to live!

The most common time/age of onset for this issue is when a dog reaches 2 yrs of age (give or take 6 months).  A 2 year old dog is the equivalent to an 18 year old human.  This is when they, and we, reach social maturity.  Many people get lulled into a false sense of security with rambunctious young dog by thinking, “he’s just a puppy, he’ll grow out of it.”  Unfortunately, this is not the case.  Little problems end up becoming big problems when dogs reach social maturity.  The reason being is that these dogs are in a struggle for status and control within the group in which they are living.  Notice I said THESE dogs and not ALL dogs.  Not all dogs are struggling for status, I am speaking only of those that are.  The issue can be initiated by a younger dog that is reaching social maturity and who wants to move up on the “chain of command,” or by an older dog in the household that sees a younger, maturing dog as somewhat of a threat.

Context is everything when interpreting canine behavior.  For example, if dog A reacts to dog B as if there is a challenge being presented, but dog B is simply approaching to greet dog A, dog A is acting inappropriate and out of context.  If dog B, however, is staring, has his hackles up, is putting a paw on the shoulder of dog A, is growling, snapping, and snarling, then dog A’s reaction would be considered appropriate for that given context.  Make sense?  Now, the degree of dog A’s reaction must be taken into account.  If dog B simply stares at dog A, and dog A goes into attack mode and wants to rip dog B’s head off, this is inappropriate and out of context.  A stare should only evoke another stare, or maybe a slightly more intense response like lifting of the head and a stiffened body posture, raise hackles, growl, scratching on the ground, etc… not an attack.  Dogs have social rules just like we do.  This would be analogous to walking over and punching someone in the face because they looked at us.  Huh, come to think of it, that does happen in humans, and it is certainly considered inappropriate by most.

The most common scenario that leads to interdog aggression involves a younger dog that had no obvious problems as a puppy, but is now reaching social maturity and begins to challenge an older dog in the household.  There is almost always no history of abuse or neglect involved what-so-ever.  Many of these challenges are subtle and may go overlooked by owners.  They include, but are not limited to, lying on the other dogs bed or “space” or blocking access to these areas; stealing food, treats, bones, or toys; pushing past the other dog to get in or out of a desired space (house, car, etc…), or standing perpendicular to the other dog (the 2 dogs make the shape of a T) with a stiff posture and resting the chin or paw on the shoulder area of the other dog.

Alternatively, the younger dog may not do anything at all.  The older dog in the household may sense the changes that the younger dog is going through and preemptively begin to react and assert status and/or become aggressive.

In general, a dog that is challenged can react in 3 different ways:

  1. He can defer/submit to the dog issuing the challenge by rolling on his back, urinating, avoiding eye contact, licking his lips while holding his head low, and allowing the other dog to do things first and have the best resources.  I want to stress that this dog is happy and content with the arrangement.  It’s the humans that have issue with it.
  2. He can fight back and one of the 2 dogs submits and the end result is accepted by both dogs.  There may be a “changing of the guard,” or there may not be.  Either way, the boundaries are tested and both dogs are fine with the out come.
  3. Both dogs can continue an ongoing struggle for status and neither one are willing to “give up.”

I would like to take a moment now to discuss the popular view point of “dominance” or “alpha dogs.”  While there is some validity to this mind set, it is not absolute and there are MANY variables involved in canine relationships.  Remember when I said canine behavior needs to be interpreted IN CONTEXT?  Well, context is constantly changing.  One dog may be “in charge” while the dogs are indoors, but another dog takes over when they are outdoors.  One dog may assert himself more when people are around, and be more submissive when there are no people around.  There is even variability concerning which people are present.  Dogs can react one way when “mom” is present verses when “dad” is present.  Also, as the dogs ages and health status’ change over time there can be changes in who is the top dog.

One special note about people.  Many times we cause problems by meddling in our dogs’ affairs.  For example, we have a dog and decide that he needs a companion.  So, we go out and get another dog.  We want the new dog to “feel at home” and to feel loved, so we shower him with attention and give him free roam of the house right away.  If our older dog takes a toy away from the younger one, we take it from him and give it back because “that’s rude.”  This can be the other way around as well.  The younger dog may take a toy away from the older dog and we intervene because of the social rules that we HUMANS follow.  Both dogs are more than likely okay with whatever was taken from him, but we start to impose out social norms on the situation and cause confusion.  The bottom line is, in the beginning, stay out of it!  Let the dogs work it out on their own.  Resist the urge to play referee by enforcing the rules of fairness :-).

So, what do we do when we have dogs that live together, yet want to fight all the time?  The first thing is to start to reinforce the position of the dog that is best able to hold his social status in the event of a fight.  In other words, reinforce the biggest and baddest.  Well, not always the biggest either, intensity and confidence also play big roles.  This may not be the dog that YOU think should be on top.  Leave your personal feeling out of it because that will only lead to a serious fight, potentially to the death.  Give this dog attention first, affection first, feed him first, etc…

Two cautions need to be issued here.  First, never, under any circumstances, should you physically punish these dogs.  This will only serve to increase their levels of stress and they could come back at you.  Once a dog figures out that teeth are pretty motivating when they touch human skin it can be difficult to get them to not use this against us.  Second, never reach between 2 dogs that are fighting.  You will get bit, you will get hurt, period.  If you have dogs that you know could end up fighting, always have them on leash when they are interacting, preferably muzzled or at the very least a Gentle Leader.  Have a broom, tennis racket, or some other such object to place between them.  A bucket of water or a hose also helps.  Also, throwing a blanket over them helps to separate them.

General Rules to Follow:

  1. All dogs involved should be separated and confined separately when not directly supervised.  The aggressive dog should be confined to the less desirable space (i.e. a spare bedroom vs. your bedroom or the basement vs. the kitchen).  All other dogs should have free reign of the house.  If there is more than one aggressive dog, they should be kept separate and the non-aggressive dog/dogs are given free reign of the house.  If they are all aggressive, they should be crated in different rooms or confined in different rooms.  Do not crate dogs that are aggressive towards each other in the same room.
  2. Put bells that sound different on each dog’s collar.  This is a great way of keeping track of who’s where without having to actually have your eyeballs on them constantly.  This doesn’t mean relax your supervision.  It just means that you can now employ your ears to help supervise :-).
  3. Choose the order in which you are going to reinforce.  You may need the help of a behaviorist to assist in making this decision because it is a critical one.  Remember, what you think is fair is irrelevant.  Here are some hints to help you with this decision:
  • If you have a young dog that starts to slightly challenge a slightly older dog, the older dog snarls and does not back down, AND most of the time the younger dog withdraws the challenge and backs off.  The older dog is larger, stronger, and of equal health.  Reinforce the older dog over the younger.
  • The older dog thinks the younger dog is challenging him, but the younger dogs is not.  The older dog is much older, weaker, and smaller than the younger dog.  Reinforce the younger dog.
  • The younger dog IS actually challenging the older dog and is becoming aggressive about it.  The older dog fights back and does not want to defer, yet the younger dog still does not back down.  The older dog is arthritic and a bit weaker, but they are pretty even in size.  Reinforce the younger dog.
  • One of the dogs is actively challenging the other, but the receiver of the challenge does not go back at the challenger.  In fact, the dog that’s being challenged defers by rolling on his back.  The challenger then proceeds to go in to the kill even though the other dog is obviously submitting.  This is a dangerous situation.  The dog that submitted needs to be reinforced (feed this dog first, let him outside before the other dog, giving him a treat or toy first, walking him first, playing with him first, grooming him first, and so on.  You can also have the dog sleep in a crate or on a bed in your room or on your bed, whereas the other dog is banished to a room or crate outside your room) in this situation.  This will not be easy to do, but if you cannot give this dog some status he will eventually get, at the very least, severely injured.  This type of aggression is abnormal.  It is inappropriate and out of context.  Do not take this lightly!  I have seen dogs kill each other in this situation.  If you cannot give the submissive dog some status you have 2 choices: #1 these dogs are to be kept separated at all time or #2 you need to find a home for one of them.  If the challenger is placed in another home he is to be the only dog in that house.
  1. All dogs should be fitting and desensitized to a Gentle Leader face harness.  The Gentle Leader is a great training tool that will give you great control over the muzzle of all dogs involved.  The dogs should be gradually reintroduced to each other while no special attention is being given to any of them.  Having them sit together (but far enough apart that they cannot connect if one decides to try) in the same room is a great exercise.  Be sure to reward the dog that is relaxed and non confrontational.  If the aggressive dog stares at the submissive one, mild aversion therapy like a water gun, foghorn or if you are using one of the best shock collar, set it to the minimum as this behavior is a mild one and you must reserve more drastic measures for more important corrections to discourage that behavior .  If the submissive dog stares at the aggressive dog, ignore it and allow it to happen as long as the aggressive dog does not growl.  If the aggressive dog growls, use the water gun or foghorn.  If the aggression gets worse, remove the aggressor and and put him in a “time-out”.  If the submissive dog stares at the aggressive dog and the aggressive dog looks away, reward (with a food treat and praise) the aggressive dog for deferring AND reward the submissive dog as well.  This is the behavior that you want from both of them.

One final note.  There are many people out there that are not all that familiar with dogs and have never really seen 2 dogs REALLY playing.  Dogs can spar and wrestle with one another, with growling, and teeth baring.  This is normal.  A lot of people misinterpret this rough play as aggression.  This is a video of my guys, Gus and Roxy playing.  This is a very tame play session.  The dogs in the title picture of this post are just playing :-).  It is important to not over react to these situations.  Your stress/tension can be misinterpreted by one or both/all dogs involved.

These are the general rules to follow when dealing with interdog aggression.  In order for true progress to be attained, you must also have all dogs consistently deferring to you.  Sign up for my tips at the top right hand corner of my home page and I will send you a copy of my book How Dogs Learn and How to Actually Get Your Dog to Listen to You.  This will cover deference and how to achieve it.  All dogs should also be examined by a veterinarian to insure there is not underlying medical cause that could be responsible for seemingly sudden behavior changes, properly exercised and have undergone obedience training.  Thanks for reading and please do not hesitate to ask questions :-).


Pictures provided by alexisfisher, dotanuki, Eloise Mason, helixblue, librarygrrrl, Max xx, and zoomar via Flickr

12 thoughts on “How To Handle Interdog Aggression

  1. I brought a rescued young dog (bitch 1.5 years) home to me pack of 2 young (bitch and dog 2.5 years) and older Bitch (5 years) the first meetings the rescue submitted to both females which are higher ranking, and not to the lowest ranking male. my older bitch does not like over dogs in her personal space and she growls to let them know this. my rescue has contentiously used her paw to “smack” all of the pack in the face. I see this as disrespectful generally in younger to older dog socialisation. my two younger dog were tolerant of this to an extent however the older bitch growled her normally warning to the rescue and the rescue would insistly up her aggressive level to match the older bitches level and then my older dog would pin her and the rescue would submit. but when with every happening of this, the rescue would submit less and less. the fighting has reached a point that neither bitch will submit and we have had to intervene. we have supported the older bitch. putting the rescue outside and feeding outside. the fighting has ONLY occurred in the presence of people. I wonder now if I have been backing the correct bitch. what would your insights be?

    • Chances are the younger dog is going to be the one you need to reinforce, but it depends on size and intensity. It really depends more on intensity. The rescue had not quite reached social maturity (2 yrs of age) when you first got her. That, coupled with the fact that the relationships between all of the dogs could change as the new addition acclimates to her new environment, can lead to very different behavior months after the initial introduction. Sometimes, even when you reinforce the correct dog, the other dog involved in the altercations will still not allow the new/younger dog to challenge her and she will not submit. These cases require very diligent management and may, or may not, benefit from anti-anxiety medications.

  2. We have four Old English Bulldogs (3 rescues, 1 raised from pup) The alpha male (7) is being challenged by the year old male pup. The two are same size and weight. It has thrown the entire pack off. The beta male if fine with everyone but the 10 year old female is now agressive toward the alpha male. The alpha male and one year old fight constantly when humans are around but get along fine with no human intervention. The fights are brutal so we have to separate them. At this point no one will give up – I’m not sure who to reinforce. My alpha (7) is a nervous wreck, vomiting, anxious, etc. The one year old is oblivious and actually looks for opportunities for confrontation. My husband favors the pup and while he was out of work took the pup every where giving him special treatment. I can see now this has created many of the problems. Do we try to start over or keep them separated. Do we start by reinforcing the alpha and see if things improve. I can’t have my alpha hurt the female she is too frail – she never challenges the pup but he does torment her and we try to keep him away from her because he is just plays to rough with her.

    • Deb, it sounds like you have a new alpha in town. The younger dog is stronger and likely has more energy/is more intense. You guys need to reinforce him. Also, and this cannot be over looked, the young guy (all of them really, but especially the young one) needs structure and exercise. As much as possible, make the same things happen at the same time everyday (feeding, walking, play time, etc…). Running around in the backyard does not count, he needs to be walked for 30 min twice a day. This will help control his outbursts. Have you read my book yet? There are many suggestions in it that will help you manage all of your dogs.

  3. Unfortunately, I seem to be experiencing the aggression in the last example under number three. I have a 1.5 year old spayed female who is aggressive towards a 5 year old spayed female. The older dog is my sister’s and the dogs do not live together. However, any time they are in the vicinity of one another, the younger dog attacks (or attempts to). The older dog tries to avoid the younger one at all costs (for example, when older dog sees younger dog through the window, older dog goes the opposite direction immediately). After the first attack, we kept them separated during visits. Now my sister is insisting that we try to fix this; it resulted in another attack that was stopped within seconds due to our preparation (knowing that it may happen, having a hold of the aggressive dog’s harness, supervising interaction, et cetera).

    The younger dog interacts well with some other male dogs. There is one male dog in particular that likes to instigate aggression against her, but otherwise, she gets a long well with other male dogs. She has never interacted with another female dog other than the one to whom she is aggressive.

    Must we always keep these dogs separate or will more training help the younger female? Who do we reinforce? Why does she only act this way towards my sister’s dog? Thank you for your time.

    • Hi Sara,

      Your dog is at a critical age. Dogs reach social maturity at 2 yrs of age and many behavior issues get worse around this time. If she was not properly socialized as a puppy she could have difficulty accepting new dogs. This can be a dangerous situation. Unfortunately I would need much more information about both dogs and both owners to make a proper recommendation. This would best be handled by a local behaviorist or positive reinforcement trainer. In the mean time, keep these dogs separated and do not try to make them play nice on your own. Best of luck!

      Dr. Mark

  4. Hello,
    I have a two year old Boston terroir/beagle mix male who is neutered and we just got an olde english bulldogge about 3 months ago, he is now almost 7 months old and is not neutered (we are exploring the option of breeding down the road) we have not had any issues until the last 2 weeks. About 2 weeks ago our bulldogge has started to become very aggressive towards our 2 year old terroir/beagle. They are fine alone (I.e. in the backyard) but when I’m around it starts with a stare from the beagle/terroir and then the OEB attacks him. It’s really wierd because it’s only when I am present, there has been no occurrence when my wife is alone with them. Do we reinforce the OEB puppy? With that, when he starts to show signs how do I go about getting him out of that state of mind? Do I crate him instantly? I’ve tried to redirect him, but the beagle/terroir doesn’t back down when he is challenged, so trying to redirect Is getting more difficult. Thanks for your time.

    • Hi Jamie,

      Your Boston/Beagle (BB) mix is likely the one who needs to be reinforced (based solely on age, but other factors could also be in play). He has just reached social maturity, so it doesn’t surprise me that he is not backing down. It is also hard to say if the OEB is being aggressive, he could just be playing. The play (if it’s play) may be too rough and your BB mix does not like it. Therefore, the BB mix goes at him in a way that’s meant to stop play behavior. This may or may not be the case, it’s hard to say without seeing it, but I do see lots of people overreacting to normal dog behavior.

      The fact that it only happens around you doesn’t surprise me either. This is very common and has to do with the dynamics of your relationship with both of them. If you are one who tries to enforce rules of fairness between them, you could be sending mixed signals. On the other hand, if neither of them are required to work for your attention, that could be contributing as well. There are many reasons that dogs react on way in front of one person, but not others, and most of the time it is attention seeking in nature.

      The best thing to do is to let them work it out on their own, unless it has reached the point of things being dangerous. If this is the case, you need to disrupt the behaviors in the VERY beginning. As soon as you see a look, or a stiff body posture, step in and get their mind on something else.

      These are quick recommendations based on very little information. I cannot stress enough the importance of getting a proper behavior evaluation. This problem will not go away and you will likely revisit it when your OEB turns 2.

      Dr. Mark

  5. I have 2 dogs, Bailey a 12 year old Bearded Collie and Maggie a 6 year old Labrador Retriever. The Lab arrived in my home when she was 10 months old. I noticed that she would become very aggressive if my Beardie was anywhere near water when the Lab was drinking or wanted to drink water. The Lab also on occasion had accidents voiding in the house. I soon found out that she had a severe bladder infection. She continued to have frequent bladder infections and remained to be aggressive regarding drinking water. When I was able to talk to her previous owner and told her about the bladder infections, she stated, “My Vet thought that she had a bladder infection but I could never get a sample.” I also found out that she had restricted the puppy from water to prevent it from urinating in the house. The bladder infections finally subsided after she had her 1st heat and was then spaded. She also stopped being aggressive around water around then. Sometime later, she would suddenly become very aggressive toward the Beardie for no apparent reason going for her neck. The Beardie never fought back. I was able to break up the fight. This would happen 2 – 3 times a year. It has just recently increased to 3 times in a very short period of time. One time I was walking with the dogs to go to bed when the Lab attacked the Beardie. The last time I was reading while the Lab was resting at my feet. My Beardie came up to be petted when the Lab attacked her. She did not have her collar on this time so that when I tried to stop her, I was bitten on the hand.

    I have brought this up to my Vet over the years. She felt that it was due to her being restricted from drinking water but once her bladder infections cleared, it continued, just not with water being part of the equation. I need to protect my Beardie and let her live the remainder of her life without fear of being attacked. Is it too late for my Lab to be treated for this? I did try to place her in a new home as a single dog but did not find a suitable home for her. Iwish that I had seen your website years ago.

    • Hi Nancy,

      This is one of the dangerous situation that I mentioned in the post. Maggie is resource guarding (drinking water, you, and the bedroom). It is never too late to get improvement. I recommend that you find a veterinary behaviorist to handle help you with this issue. If one is not available in your area (they can be hard to find), or a reputable trainer (which can also be hard to find). This is a serious situation that will get worse over time and will be best dealt with in person. Here are 3 websites that can help you find the help you need:

      In the meantime, it is imperative that you avoid all situations that will lead to an aggressive event. If that means keeping them separated, then that’s what needs to be done. Best of luck to you!

  6. First let me say that I am not new to raising or training dogs and have seen this same situation and overcome it many times in other dogs over the last 30 yrs. This time I feel I have met my match. I have a 2 yr old spayed female Pug and an 8 yr old neutered male Chihuahua. I have had both since they were 8 weeks old. Things were fine until about 6 months ago when the Pug attacked the Chihuahua seemingly for no reason. She had been in another part of the house and he was asleep in the den when suddenly attacked him. The Pug weighs 20 pounds and the Chi weighs 5 pounds and has a seizure condition so letting them fight it out is not an option. Even if the Chi rolls on his back and avoids eye contact the Pug will continue attacking him. Putting a muzzle on the Pug is obviously not an option because of the shape of her face. The only muzzle made for her also covers her eyes. I am at wits end as none of the suggested training methods have worked. I love them both dearly and having to live keeping them seperated to protect the Chi is driving me crazy. The Pug is very friendly with people, children and other dogs inside or outside of our home. Her aggression is directly only towaed the Chi, seems to have no triggers or predictors that we can recognize and is so focused on getting the Chi that she will totally ignore redirection. Do you have any other suggestions that I haven’t tried?

    • Hello Shea,

      I can certainly understand your frustration. This is a good example of what can happen when a younger dog reaches social maturity, which happens around 2 years of age. A really common thing for us humans to do is to decide which dog should be “in charge.” For example, the chi-chi is 8 yrs old and has been in the house for 6 years longer than the pug, so many would try to tell the pug that this is the chi-chi’s house and the pug should accept that and respect the chi-chi as the leader. Say the chi-chi has a toy, and the pug steals it. Many of us would take the toy from the pug and give it back to the chi-chi. Many times the chi-chi doesnt have an issue with this situation and allows the pug to take the toy. We interfere and institute our rules of fairness. However, this may not be the way the dogs see it. Reinforcing the wrong dog will lead to conflict. You have 2 options, #1 is to use positive reinforcement and begin to reinforce the pug as the dominant dog (as described in the post), or #2 punishment (either positive or negative). What have you tried in order to resolve this situation?

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