20/04/2025
Finally! This is a subject that's close to my heart, as a scientist it really gets under my skin when people throw around the term "littlermate syndrome" as if it's a well documented medical condition.
It's not, it doesn't exist, there is no syndrome but raising two pups together is difficult! It requires a whole load of time, patience, individual attention and dedication. It's absolutely not for everyone, but that doesn't mean there are automatically going to be problems because your pups are related, or even just the same age.
A lot of this myth is down to poor breeding, followed up by a total lack of training or understanding of dog behaviour.
Recently, things have been changing. In the last few years there has been a noticeable increase in people on social media and the internet perpetuating this old wives tale as if it is fact. The wiki page calling it out for the nonsense it is has even disappeared and a lot of force free trainers have decided to try and adopt the term to encompass the host of behavioural and training issues that could arise, which I think is dangerous.
We, as a community, can absolutely all do better in this! 💖
I have been wanting to do a literature review style blog post on this for years, but thankfully someone (much higher profile) has beat me to it because believe me that is a lot of work!
(Especially when you have to read around the broad spectrum of information on everything lumped together and incorrectly labelled under a nonsense term which doesn't actually exist in the peer reviewed literature).
Thank you Zack, for continuing to make science accessible for everyone!
Have a great Sunday guys! 🐕
“Littermate syndrome” gets tossed around like it’s a scientific fact. But spoiler: it isn’t 🚨
What is real? The very predictable challenges that come from raising two adolescent brains at the same time. In practice, it can feel like three times the work.
Calling this a “syndrome” mislabels a training issue as a medical one, which gets in the way of actually solving it. In reality, it’s just predictable fallout from raising two young dogs without intentional, separate training.
Sibling pups (or even just two dogs that spend a lot of time together) bond hard. If you don’t proactively practice solo time, they can melt down the second they’re apart, and tune you out when they’re together.
Try teaching “sit” while your students are busy wrestling. You probably won’t get very far.
Separate, short sessions are mandatory if you want either pup to learn anything.
As their hormones kick in, best buddies can even morph into “frenemies” 😬 But proactive behavior work will help you communicate clearly, notice potential conflicts early, and keep minor spats from becoming major fights.
To be fair: there are upsides. Built‑in playmate, consistent enrichment, and the sheer joy of watching a friendship bloom between two animal companions that you love.
If you find yourself in this situation, trick is stacking the deck so the benefits outweigh the headaches.
Understand that 2x the dogs = 2x the work. You can’t expect one of your puppies to “help” take the load off of raising the other.
My advice: in the beginning, walk, train, and cuddle each dog separately every day. Your bond with each dog is the antidote to codependency.
Supervise play, manage resources, and consistently step in before roughhousing escalates so your puppies learn how to take cues from you even while they’re feeling rambunctious.
This part cannot be overstated: If you want to succeed, you MUST commit to training each dog one-on-one.
Rest one pup with an amazing chew while you work the other. Then switch. Everyone learns to chill alone. Everyone gets focused time where they can actually learn without constantly being distracted by their sibling. Both dogs will learn quickly and feel satisfied - and you will, too.
Bottom line: adopting littermates isn’t a moral failing, but it is a SIGNIFICANTLY bigger project, and you have to treat it accordingly in order to succeed. If you have the bandwidth and a solid plan, you can absolutely raise *two* rock‑star dogs.
If you’re on the fence, start with one pup. You’ll be glad you did. Take the time to nail their training, and then add a second dog once the first is a confident, well‑adjusted sidekick.
How many dogs do you have? How far apart in age are they? 🤔
Sources below! Join the Dog Training Revolution at zakgeorge.com 🙌
“There’s No Scientific Reason to Believe Littermate Syndrome Exists”
by Kayla Fratt, IAABC Foundation Journal
https://journal.iaabcfoundation.org/littermate-syndrome/
This article argues that “littermate syndrome” lacks scientific backing and that the behavioral issues attributed to it are more likely due to inadequate training and socialization practices.
“Littermate Syndrome”Penn State Extension
https://extension.psu.edu/littermate-syndrome
This one acknowledges the absence of scientific literature on littermate syndrome but notes that anecdotal evidence from professionals suggests behavioral challenges can arise when raising sibling puppies together.
“Understanding Littermate Syndrome In Puppy Pairs”Texas A&M University College of Veterinary Medicine & Biomedical Sciences
https://today.tamu.edu/2023/09/28/understanding-littermate-syndrome-in-puppy-pairs/
This article discusses potential behavioral issues in puppies raised together, such as separation anxiety and fearfulness, and emphasizes the importance of individual socialization and training.
“What is ‘Littermate Syndrome’?”Veterinary Partner - VIN
https://veterinarypartner.vin.com/default.aspx?Id=11564754&catId=102897&pid=19239
This source explains that while “littermate syndrome” isn’t a recognized medical condition, the term describes behavioral challenges that can occur when two puppies are raised together without proper individual attention.
“Littermate Syndrome in Dogs: Fact or Fiction?”Mad Paws Blog
https://www.madpaws.com.au/blog/littermate-syndrome/
This blog post asserts that there’s no scientific evidence supporting littermate syndrome and suggests that observed behavioral issues are more likely due to the challenges of raising two puppies simultaneously, and provides some tips for avoiding issues.
“Littermate Syndrome”Wikipedia
https://en.wikipedia.org/wiki/Littermate_syndrome
The Wikipedia entry gives an overview of littermate syndrome, notes the lack of scientific consensus and highlights that the behaviors associated with the term may result from environmental and training factors rather than sibling status.
What is your experience? Tell me in the comments!
