Littermate Syndrome

Double the Fun or Triple the Trouble?

The scoop on littermate syndrome!


Oswin and her littermate playing at 9 weeks old

Oswin and her littermate playing at 9 weeks old

I will admit it, if there was a Puppy Addicts Anonymous organization, I would be President and meeting leader. “Hi, I’m Tena and I’m a puppy addict.”

I love puppies–I don’t just love puppies, but I love raising puppies.  Socialization, mental stimulation, house training, chew training, sleep-time training, crate training, foundation manners–I love doing all of these things with puppies (even the barking/crying that comes along with some of these).  If I could get paid to raise puppies for people, I would do it in a heartbeat!  It was one of the things I loved most about fostering puppies… raise them, work hard, and then send off little well-adjusted “tweens” to their new homes before they become ungrateful adolescent snot-heads (*I can say this since I currently have an adolescent snot-head).

Even though I absolutely love raising puppies, there is one thing that I would not choose to do (unless an unavoidable situation), and that is raise two puppies at the same time through adolescence or beyond.  Raising one puppy into a well-adjusted adult dog is a lot of work, raising 2 of them is triple the work!  Knowing what I expect my adult dogs to be able to do (work for me with reactive dogs, demo in stressful public environments, perform in dog sports consistently), the amount of socialization and training is huge to raise a puppy who can do the things I hope they can do for/with me.

4 week old mixed breed puppies all snuggled up on Tena's lap! They love to snuggle and play together, but will be going to new homes on their own.

4 week old mixed breed puppies all snuggled up on Tena’s lap! They love to snuggle and play together, but will be going to new homes on their own.

Although the possible effects of raising two puppies together is called “Littermate Syndrome,” it is not just applicable to biological littermates.  Two young dogs (or a very insecure dog of any age) who are brought into the home at around the same time (I’ve seen littermate syndrome symptoms with dogs acquired a year apart) can very easily display the same symptoms and require the same level of care to prevent those issues from developing.  Certainly, some people can luck out and have two “littermates” who are easy and grow up without problems, but when things go wrong, they can go very very wrong.  Considering the potential outcomes, I do err on the side of caution and do not suggest taking on the challenge of raising two puppies at the same time.

There are quite a few fantastic blogs and articles about Littermate Syndrome written by quite a few experts in the field (links at the end) that detail the “why not” reasons, or discuss common misconceptions that some breeders, rescues, or shelters might suggest (“two are better than one so they can keep each other company,”  “they are already bonded so should stay together,” etc), and list specific ‘symptoms’ to watch out for, so I want to take a little different approach.  I want to discuss what I would do if I were ever in a situation raising two puppies to prevent problems from developing and to share some of the cases I have seen over the years involving “littermate syndrome” (with names/details changed of course).

So you already have two young dogs (biological littermates or not)…what should you do if you want to raise them to be friendly, well-adjusted,and well-trained adults?

**Crate separately–Both dogs need to have their own crates and their own confinement areas.  I would actually be setting up THREE confinement areas and THREE crating areas.  There are times where I would let them be confined (separately) next to one another and other times where I would want the confinement areas to be completely separated so they are totally alone.  So I might have two confinement areas in one room and another confinement area in a separate room (the same set up for crates).  There will always be some situations where the dogs will have to be 100% alone, they need to learn how to be 100% alone so simply having separate, but neighboring, confinement areas will not suffice.


**Dedicate 2-3 hours a week for dog training classes-Each puppy should be enrolled in a separate training class (and/or private in-home training sessions).  Each puppy needs to learn how to exist in the world without the sibling with them, they need to learn how to play with other dogs and interact with people confidently as individuals.  In addition to individual training classes, they should take periodic training classes together so they learn how to work in a classroom environment together, co-exist with other dogs together, and interact with people appropriately while together.   If we include travel time and some cushion time, that’s almost 4 hours a week dedicated to two separate training classes (not including the time spent at home training them separately and then practicing together every week).

When ‘littermate’ puppies are so closely bonded together, it makes training them way more challenging because they often are much harder to motivate to work for their humans and the logistics of training two puppies at once is not easy or convenient–while you work one dog where is the other dog and is that dog throwing a hissy fit because the other is getting treats/attention (or are they throwing a hissy fit because they are separated from their sibling).


**3 Socialization trips per week X 3–I typically suggest socialization trips every other day for puppies… they should be going on 3 or 4 adventures every week to experience new people, places, things, sounds and situations (not all need to be BIG adventures, even just ride-along on errands).  Well, you will need to triple that for two puppies.  Each puppy needs to have individual socialization experiences and then they need to have socialization experiences together.  If they only experience the world with their sibling present, many puppies become unable to handle the world if they are alone.  Former foster dog Linus was very much so like this, when in the world with one of my dogs, he was a little nervous, but when he was alone he was a trembling puddle of nerves (here are a couple Linus blogs about this Dependent on Group and  Linus’s First Trip Out).

The other extremely important part of this process (individual adventures) is for the puppy left at home alone to learn how to be at home alone without panicking.  This is a problem I have seen frequently with ‘littermate’ dogs–they cannot be left home alone without their sibling without complete melt downs (or simply cannot be left alone because it turns into dangerous and self-harming separation anxiety).


**Play with humans and cuddle with humans–One of the main concerns with “littermates” is that they bond so closely together that they do not bond with their humans as well.  With this in mind, I would actually be limiting the playtime they have together.  I want them playing and cuddling with human family members far more than playing with their canine sibling so they can bond with their humans, learn how to interact with people appropriately, and spend time building an excitement for playing with toys with their people.  The puppies would have opportunities so play together for sure but it would be far more time separated until the bonds with their humans and their desire to play/work with their humans was solid.


Although it might seem like two is better than one or that it won’t be that much harder to raise two puppies, it is not that simple.   After-the-fact intervention if things are going south does not always result in desired outcomes–dogs may still need to be rehomed, some may not be candidates for rehoming, and some may need life-long management to safely co-exist.  Regardless of what an unethical breeder, unethical rescue/shelter, or unethical pet store may say, two is not better than one and is not just a ‘little’ more work.  Please consider all the extra time, energy, commitment and resources that are needed to ensure raising well-adjusted adult dogs together from puppyhood (not just gamble with a lucky pairing that happen to make it easy for you).  It can certainly be done, and sometimes you might luck out, but it’s certainly not a walk in the park to set yourself up to have well-adjusted adult dogs.



So what can possibly go wrong with “littermates”?  Here are some case studies of clients (with details changed)


Case 1:
Max and Sasha

10 month old, opposite sex, biological sibling Cairn Terriers

Primary complaint:  Max and Sasha presented with fear of new people that resulted in barking/lunging, general training troubles (hard to teach and would not give their owners the time of day), separation stress, resource guarding (with each other), bullying, and aggression.

Max and Sasha were completely inseparable but they did not have a terribly healthy relationship.  Sasha would guard food and toys aggressively against Max because Max was typically a bully toward her.  He would attempt to steal her things and would target her with unwanted rough play.  He’d pin her to the ground, bowl her over, and not listen to any of her communications asking him to stop.  Eventually this over the top and unwanted rough play started spilling over into aggression when Sasha would finally correct him, he would go back at her aggressively and result in scuffles (with no injuries).  Although Max was regularly beating up on Sasha, she hated to be separated from him and would panic if they were separated (as would Max).  Other than at meal times, the puppies did not really spend a ton of time engaging with their humans to get the things they need.  They would accept cuddles but not solicit much from humans.  Outside of the home, if separated, Sasha was a very fearful puddle of a dog–she really could not function and thought the world was terrifying.

Outcome:  We attempted some separation training, building up value for people, and working on the dogs being calm around one another, but it was ultimately decided that rehoming one of the dogs would be best for everyone involved.  Once separated, each dog blossomed beautifully and became more confident and well-adjusted in the world.  It was not an easy choice for the owners but it was the right one for them and, most importantly, for the pups.  They both really became fantastic dogs in their ‘new’ homes and the problems were all reversed beautifully.

This was definitely going to be the most positive outcome possible for these dogs!  Both of them are happier and healthier living separate lives and the owners did not have to feel the pressure of meeting the behavioral/training needs of these littermates.


Case 2:

Jasper and Luna

16 month old mixed breed male acquired 12 months prior and 11 month old golden retriever acquired 6 months prior (Jasper was 10 months when they got 5 month old Luna)

Primary complaint:  I was called in due to human aggression concerns with Luna but discovered additional concerns.  She was a very nervous nelly and would act aggressively toward people on the street and in her home (she had not bitten yet but there had been a few ‘close calls’).  If she was with Jasper, she was nervous, but not as aggressive when outside the home (more flighty), but was more confrontational with visitors to the home if Jasper was around.  If separated from Jasper she would panic (pacing, drooling, vocalizing, panting, unable to eat) until he returned (which was definitely not great when he was gone for more than a full day for his neuter).  Although she always wanted to BE with Jasper, they did not really interact in meaningful ways terribly often (interactive play, mutual exploration in the house/yard, or cuddling).  The owners had very little success with training for Luna (she would enjoy cuddling from humans but was not really interested in playing with them and certainly not working for them).

Outcome:  We implemented mandatory separation schedules for both dogs (starting with small separations during meal times for counter conditioning and desensitization and built up to lengthy separation), we played many confidence boosting games with Luna to build her confidence away from Jasper, and their owners committed to a lengthy training protocol to work on counter conditioning, desensitization, and teaching incompatible behaviors to combat the human aggression.  Their owners committed to investing a large amount of financial resources (in training, gear, day care for separations, and more), a large amount of time, and showed an openness to changing routines and the status quo to work through the issues at hand.  Although not perfect, Luna’s aggression was improved greatly and was much more manageable and she was able to be separated from Jasper with no problems.

I was exceedingly pleased with the outcome here.  While not perfect when we wrapped up our lessons, the owners had a clear plan to follow to continue to improve Luna’s reactivity on walks, and a routine for how to bring guests into the home safely but most notable was her ability to be comfortable and happy without Jasper with her.  I was a little surprised how quickly this one turned around.


Case 3:

Abbie and Lexie

3 year old Border Collie female and 2.5 year old border collie female  (Lexie was acquired at 2 months old when Abbie was 7 months old from the same breeder)

Primary Complaint:  I was called in after a fight that resulted in 10 staples and 2 drains in Lexie.  This was their third fight in about 9 months and had the most damage.  The girls had lived together uneventfully for 18 months or so.  Abbie was always pushy toward the more timid Lexie–Lexie actively tried to avoid her advances but also wanted to be her shadow and would always be with her and was very bonded to her.  Although not the main reason for my visit, it was discovered that Lexie was highly reactive to people, dogs, and novel things (hello Christmas decorations) in the environment whenever she was in the world without Abbie.  When Abbie was with her, she would walk through town, ignore people (unlike Abbie, she would not approach strangers, but she would stand quietly), and would investigate novel items if Abbie did–but without her she would slink around town and bark/lunge at people and dogs.  As long as she was out of the house (on walk or in the yard) when Abbie left, Lexie had no problems being left alone–if they tried to take Abbie for a walk while Lexie was home, she would be anxious and stressed the whole duration.  Although their relationship was complex, Lexie continued to cling to Abbie and would seek her out when she was stressed, rather than seeking out her humans for help.

Outcome:  We implemented safety protocols, initiated crate and rotate schedules, and started a protocol to help the girls learn to respect each other and be calm together.   Unfortunately, there was a failure in management when a door failed to latch and Abbie escaped her room before the second barrier was able to be closed (they had a double door separation system to prevent this, but sometimes management fails).  The girls got into another brawl, this one worse than the last and this time resulted in a fairly severe bite from Abbie to the owner who was trying to break it up.  It was an incredibly hard decision for the owners to make because Lexie was so anxious and she had her own behavioral problems, but because Abbie was absolutely not a candidate for rehoming (due to the damage she inflicted on Lexie and the bite to her owner), they ultimately decided to try and place Lexie in a rescue.  The rescue that took Lexie made it clear that they were not a sanctuary and that while they would do everything in their power to help Lexie gain confidence and feel safe in the world, that if her reactive behavior escalated, they would be forced to deem her unadoptable.   The attacks from Abbie had created a very leash reactive dog and one who was not dog friendly and the stress/panic of being separated from Abbie did not sit well with Lexie (on top of Lexie being an insecure and nervous dog while out in the world by herself in the first place).  Historically Lexie had avoided strangers, even if reacting, but she started becoming more forward with her reactions towards strangers on walks and more fearful and defensive toward people who had to handle her.  She was ultimately deemed unsafe to place and was humanely euthanized.

This situation was a real heart breaker because neither dog was a bad dog but it was just not at good situation and developed into a dangerous situation.  If there had been earlier intervention (even if just to boost confidence with Lexie and get her appropriate socialization) the outcome may have been different for her/them.


If you would like more resources on Littermate Syndrome, here are some of my go-to resources:

Pat Miller’s article in The Whole Dog Journal

Patricia McConnell’s blog on Littermates


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