Dealing with Dog Sibling Rivalry

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Just like people, some dogs really struggle with sibling rivalry. In fact, dogs that go home with their siblings often struggle with aggression issues more than dogs who are raised without a “sibling” – whether or not they’re actually related.

In the latest “Ask a Trainer” question, we’re helping a reader troubleshoot the sibling rivalry between his two teenage dogs.

Our reader writes,

How do I stop my two pups from fighting with each other? They are brothers and have been together since birth. They are normally very well behaved but have recently started fighting with each other to the point of drawing blood. They are not quite a year old and we are obviously still in training mode. They know all of their basic commands and are fully house trained using a bell to ask to go outside. Any advice would be greatly appreciated as I am at my wits end.

Dealing with dog-dog aggression and sibling rivalry isn’t easy. Get the help that you need with a Certified Dog Behavior Consultant in your area. If there’s no one near you, I can help.

I offer 15 minute behavior help calls1 hour calls, and month-long email support packages to suit your needs, no matter where you live.

Having two dogs that fight with each other is incredibly stressful for a home. Unfortunately, dog-dog aggression is often worst with dogs that are the same gender and the same age. Things can be even worse when the dogs are siblings.

What’s Littermate Syndrome? Does It Exist?

Anecdotally, it seems more common for pups (related or not) who are similar in age and raised together to become aggressive towards each other as adults. Sometimes, they also become so emotionally reliant on each other that everything else is SCARY.

This phenomenon is commonly termed “littermate syndrome,” but there’s actually no research to show that littermate syndrome exists. In fact, breeders commonly raise siblings together with no problems.

I recently did a lot of research on so-called littermate syndrome for the above-linked IAABC Journal article. I’ll quote liberally from that piece here:

“My personal hypothesis is that perceived littermate syndrome is actually generally a result of several specific conditions that often arise when people attempt to raise siblings together. Of course, all of these observations are, by necessity, anecdotal and based on personal experience.

  • Inadequate socialization, especially with other dogs. Many unknowing owners assume that letting their two puppies play together is an adequate replacement for dog-dog socialization. This misunderstanding is particularly understandable when the two puppies are the same age and breed. In other words, it’s particularly easy to fall into this trap when raising siblings. The owners I personally know who have successfully raised sibling pairs took pains to introduce the puppies and teenage dogs to other dogs, both together and separately.
  • Inadequate environmental management. It also seems that some owners are more likely to slip up on environmental management (removing food bowls, managing access to resting places) when the dogs are perceived as “best friends who have never been apart”—as is the case with siblings.
  • Insufficient “alone time” training. Many of the hyperbonded dogs I met at the shelter were crated together, walked together, taken to the vet together, and so on. The owners sometimes reported that they had “never been apart.” And therein may lie the problem. Just like we’d expect to see separation anxiety if a dog had never been more than three feet from their owner, it’s not surprising to see extreme distress in these adult siblings that have never been taught how to be apart. I’ve found that most of the owners that successfully raise and keep siblings do things with those dogs. They go to training class, shows, trials, and more with just one dog at a time. At the very least, the dogs are used to being trained and crated separately.
  • Failure to meet the dogs’ needs. Many of the cases of sibling aggression that I’ve seen are also paired with a clear lack of mental and physical enrichment for the dogs. In conversations with the owners, I often realized that they assumed that the two siblings could keep each other company. The owners didn’t see a need for puzzle toys, training games, long walks, and so on because the dogs have each other.”

In other words, no, there’s not a diagnosable syndrome for littermates. We can’t open up a pup’s brain and point to the problem.

But humans who raise two similarly-aged puppies together often make similar mistakes that lead to specific behavior problems (like sibling rivalry, aggression, or whatever you want to call it).

Why Are We Seeing Problems Now?

Dog aggression generally starts to manifest around 8 to 20 months of age – when dogs are teenagers.

All of this is to say that our writer is dealing with a tough situation. Sibling aggression is a common phenomenon in dogs, and is incredibly difficult to deal with. Unfortunately, good training alone won’t prevent this problem. Your dogs can know all sorts of cues and tricks and still have issues with aggression.

There’s a basic framework for helping dogs that fight with each other if they live in the same home:

  1. Separate the dogs completely for now. This might mean a “crate and rotate” setup where one dog is in the crate (or in a separate room) while the other is free, and vice versa. This keeps everyone safe starting right now.
  2. Identify what caused the fights. Now that you have a bit of space to think, it’s time to identify the “triggers” in your dog’s fights. Common triggers include food, toys, attention, sleeping space, doorways, or exciting things outdoors (like squirrels or visitors).
  3. Start muzzle training the dogs. Be sure to get a comfy basket muzzle that fits your dog (see our muzzle fit guide here). I use extra-tasty treats that are easy to get through the bars of a muzzle (explore our favorite muzzle-friendly treats and check out our demo on how to give treats through a muzzle). This will allow you to start reintroducing the dogs with maximum safety for the dogs.
  4. Teach both dogs hand targets and go to mat behaviors. Do this separately and ensure that the dogs can easily “relax on mat” and “target” while there’s food or toys on the floor before you start introducing the cues to social situations. Read more about “proofing” behaviors here to ensure that you build up the difficulty of training properly. This allows you to separate the dogs without putting your hands in danger. Pulling the dogs apart can also add tension to a situation, which can actually cause a fight!
  5. Reintroduce the dogs in neutral situations. Take the two dogs on walks together (the parallel walk method is great for his) and do other things where the likelihood of a fight is extremely low. This allows the dogs to continue having good experiences with each other. Practice hand target and go to bed behaviors while both dogs are feeling relaxed and happy. Continue avoiding triggers whenever possible.
  6. Use counterconditioning and desensitization to help the dogs relax. Pick a single trigger and tie both dogs down to a door. Have them lie on their mats. Then reintroduce a trigger at a low intensity. For example, put a food bowl down far away from both dogs. Then feed both dogs copious amounts of chicken and other yummies. This way, they learn that Brother + Trigger = Chicken. This will help them learn to relax. This is pretty tricky to do well, and I highly recommend getting the help of a Certified Dog Behavior Consultant.
  7. Use hand targets and go to mat behaviors to split up the dogs if needed. Practice sending the dogs away from each other to their beds around their former triggers. Try your best to avoid triggers unless it’s a training situation (this is called management) and don’t be afraid to call the dogs apart before things get tense. So if you see Fido giving Rover the stink-eye, call them apart before things get nasty.

Unfortunately, not all dog-dog aggression cases resolve nicely. In many cases, it’s actually best for the dogs to rehome one of them. This allows the dogs to live full lives without constant management, crating, and squabbles.

Many dogs that fight with their siblings are perfectly friendly to other dogs. Some are even friendly and playful with their siblings in moderation, but not 24/7 (this may sound familiar to those of us who love our families but cannot imagine moving back in with our siblings).   

7 steps to stop your dogs from fighting with each other |

26 thoughts on “Dealing with Dog Sibling Rivalry”

  1. I am working with two adult female boxers, One has had a litter of puppies, the other one has not. They have bo been fixed, and a month after fixing both of the female dogs, boxers they have become aggressive towards each other. They are both from the same litter. What are some ways that I can stop the attacks before the owner gets hur

  2. My family got two husky puppies in feb. The idea was to only get one. But at the last second my father chose to get a second one. I always wanted a husky which was why i was getting one. It surprised me they got the second. For the first few months everything was great. They played together. Cuddled. I took them both for walks separately. Only walking them together 3 timed. Each time they both walked without fighting. They would wrestle all the time. It was not until recently that they would wrestle then fight if it went too far. All they want to do since they turned 4 months old is wrestle. They rarely chase each other anymore. I try to train them separately. One was even going to puppy class. But due to the virus it was cancelled. Because of everything going on in the world i cannot take them to be or play with other dogs. Their triggers seem to be food. Treats or attention and when they get too excited if someone in the family comes over. Then they will cuddle with one another again. They are to be fixed this coming month. I am hoping it helps to some degree.

    • Hi Jess, there’s not much evidence that fixing them will help this problem, because it’s not related to sexual hormones in most cases. 🙁 But the suggestions in this article should help!

  3. Hi Kayla,

    My family got Jack Russel Terrier – Chihuahua mixes last summer, and they just turned one year old about a week or two ago. We also have two seven year old dogs that they were separated from for the first few months of living with us. However, in the past few days, the puppies have begun fighting with each other all the time. We began separating them during the day, only having them together to eat and go outside. When eating and being outside they are beat of friends, but right after, they begin fighting again. They get along perfectly with the other dogs and the humans, and we really aren’t sure what else to do. Thanks!

  4. Hi, we (bfs family and myself) have 2 dogs, there both turning 1 year on July 1st, both males and there a mix of Border Collie, German Shepherd, and giant Schnauzer. Recently they both got fixed due to the fact that they were being aggressive towards one another and the fights weren’t so bad, when you took them apart they just left each other alone. After a day and a half of them being away at the kennels from the house they had another fight, this time it was so bad that one of the dogs actually got hurt and we had to get 4 people in total to grab both collars and rip them off one another. For the last week almost this has been happening non-stop and its ruining our lives because we are all terrified that one day it will be so intense that one of us will get hurt. We are currently separating them due to the fights and will look into getting muzzles, if the muzzles don’t work we will have to re-home one of them, I was wondering what causes these fights to happen because before they would play fight but now its a fight to the death with both of them.

    • Honestly, you need to hire an experienced aggression trainer (Michael Shikashio takes remote clients, he’s AMAZING) or consider rehoming one of the dogs. This situation is just too dangerous to leave as is. The dogs aren’t likely to improve with a break and some muzzles 🙁

  5. Hi, we got two miniature dachshunds (brothers) in January this year. They are close to turning 8 months and one of them has started growling and attacking the other, but there has been no injuries. The fist time was when they both ha a chew stick and randomly one if them started to attack the other. We feed separately all he time apart from chew sticks and treats. The second time they had both finished eating, so we allowed them back in the same room, however the dog that keeps growling and going for the other sniffed the others mouth before going at him again. We believe its food but there seems to be tension between them both. What would you recommend we do as once they are fine again they are playing and cuddling.

    • Hi Jasmin, outside of the suggestions in the article above, I can’t help much without scheduling a paid consultation with you – it’s just too complicated to handle in the comments section of a blog!

  6. We got 2 puppies (different breed) but same age (about 3 weeks old) and both males 6 years ago. Like the article says they have never been apart and we assumed were inseparable. One of the dogs has always had a more controlling and bad temper but this brother has always been more calm yet very playful. Recently our bad tempered dog has gotten worse than ever before. He has always been possessive with his food, and toys and a few times would get so mad out of nowhere that his brother couldn’t even look him in the eyes or it would increase his growling. Now they wake us up at 1am, 3am in the morning and they have been fighting more often and I’m not quite sure what is the trigger. I mean like I mentioned one dog gets easily triggered but lately he has been horrible- isn’t he too young to be getting bad already?

    From what I can tell is that the cranky dog wants to be alone? And the other follows him knowing it will make things worse. I separate them but as soon as the cranky one sees him he will growl violently even being left without breath.

  7. Hi Kayla I just rescued two male beagles whom came from a very abusive home and flown to Michigan and placed in a rescue . I started off being their foster mom but have since decided to adopt them my question is the older one whom is about 7 gets very angry at his younger brother if 100% of the attention is not on him and he will go after her his brother and try to bite him they wanted these two to be rescued together and I don’t have a problem with them being together but I really need to protect the other one as well any suggestions on how I can get him to calm down and trust that no one here is going to hurt him. I already see a big difference in him trusting my husband and myself I just need to get this other issue with his brother resolved any suggestions would be greatly appreciated.

  8. Hi I have 2 litter mate springer spaniels one male one female. They don’t fight over toys or food but sometimes when let outside in yard the female with wrestle the male to the point we need to separate them! There is no blood or injuries but wondering how to stop this.

  9. Help! I adopted a brother sister border terrier mixes at 4 months – – they were found in the woods together by animal control – we had just lost our adopted pup of 13 years and I thought how great to get both and keep them together. They are now a year and a half – they love each other mostly – I would see some growls over bones and riding in the car so we took all bones and toys away – and now crate the in the car – and recently started aggressively fighting over jealously. If one is sitting by my foot and the other comes over and it just happens so quickly. We have had a few fights but we have been able to either prevent it or break it up quickly – but Just now the two of them went after each other and wouldn’t stop until a got a chance to break them up. There is blood everywhere – they got each other pretty good in the face. I have clean them up and they are ok for now – they have appointments tomorrow. But what do we do now? can this be stopped – I love them so much in each of their won ways but I don’t won’t them to hurt each other or one of us trying to break them up… any advice would be appreciated.

  10. Hey there! I have recently adopted 2 stray dogs, both girls and 10 months old, and they have been getting along except for the fact that a few days ago they had a massive fight, which led to superficial injuries. Since then they have been tense and been fighting several more times, however, we have bought muzzles for them. After the fight, they get makeup almost immediately and start playing and eating together again. The girls lived together at a foster home before, and the rescuer said they have fought before but only after we adopted them. Both are spayed and are non-aggressive towards other dogs, as we have an old golden retriever and they have never growled or attacked him. even during their first fight, they have not attacked him or any human, only focusing on each other. The one dog, which is more introverted than the other one and follows the other dog around and hates being without her, is possessive over her bed and toys and gets jealous easily. The other dog, which is extroverted and jumpy and listens well, provokes the other one often by squeezing in between her and me when I pet her or blocking the way at the door, or lying on her bed, which has often led to the introverted one to growl. They have fought in the kitchen an hour after eating and after barking at the Gardener and on the bed while playing, which led to fighting and tried to fight while eating, where they usually switch bowls while eating. I really don’t want to give one of them up, as they rely heavily on each other, especially the introverted one, as she gets depressed without the extroverted one. While playing, they act nicely, but the extroverted one isn’t as interested as much in the golden retriever as the introverted one while playing, and the extroverted one actually starts humping the introverted one when she plays with the golden retriever. We have started positive reinforcement and separation, but how else can I help them? My father is on the verge of giving them up, refusing a dog trainer, as he is angry about the fact that they fight, and I love them so much

  11. I have 16 months old three dogs who are siblings and they sometimes fight aggressively and I am afraid that it might get worse. I would like to know how I can create a friendly environment among them.

  12. I have two female pit bull littermates. We were only going to keep one when our female had the litter, but ended up with both. We got the mother dog fixed after she gave birth, For the first few months everything was fine. Then one of the puppies went after the adult mother dog. After that the two siblings have been aggressive towards each-other. The puppies are coming up on a year old and we have been doing the crate and rotate method with them and the mother. We have been wondering if spaying the two females will help, as it seems like it is a dominance fight between the two puppies. We also have the male father in the house and wonder if fixing him also will help. We just want to know what will help until I move out of my parent’s place and take the puppy that is mine with me.

  13. Hi- we have an GSD foster puppy from 9 weeks to now 7 months that has become what I would call obsessive with her brother….copies him, barks if I take him out to pee without her(she is fine going out with me on her own), has to walk right next to him on walks. They drink out of same bowl and are not food aggressive with one another. They play with toys together. He lets her take toys out of his mouth. The issue we have is when he runs she attacks and bites him in the back. If I let them off leash I have to do it separate….when he’s off she lunges and barks. When she is off she doesn’t play with other dogs but dive bombs him. I’ve never seen this behavior before and we really want to adopt her but are worried that it will get worse or if we seek training it won’t be able to be fixed. Any thoughts?

  14. Currently seeking out a local CDBC that can help with some recent aggression in our two girls (8yr old lab/Shepard mix & 4yr old pocket pittie). At first we thought it may had been sleeping startle reflex bc the fights always occurred from waking. This morning a fight broke out while both awake & we cannot figure out trigger nor have we observed anything to help figure out the cause. They have upcoming appts w vet to rule out health issues but I’d like to look for CDBC since there has been territorial displays (from 8yo) before. What are key things I should look for to choose the right CDBC?

    • Hi Ana, it depends on where you are. In some areas you might only have one CDBC to work with. If you have the choice, I’d certainly opt for a CDBC who specializes in aggression (rather than anxiety) for your case. Graduates of Michael Shikashio’s aggression mastercourse will also be very helpful!

  15. Hi Kayla,
    We adopted a mini English bulldog at 9 wks and she is now 11 months. We brought home her half sister a month ago, she just turned 1 yr. They either love each other or at the drop of a hat are at each other relentlessly. We tear them apart by pulling their back legs to separate them. They have not got into it when outside. It is usually “space related” or jealousy of me. They both get individual attention. When we break up the fight, they both go to their kennels until calmed down or a couple of hours. We let them out and they are fine together. Will they outgrow this? How can we help or redirect? It is so frightening. They have no toys because they fight. They go on walks and do play ball outside but we cannot leave the balls out because they will fight. Please help.


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