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Littermate Syndrome: Real or Myth?

Imagine getting two cute, adorable puppies from the same litter and bringing them home to be a part of your family.

You might think you’re doing a fantastic thing, keeping brother and sister pup together.

Cuddling will be double the fun!

I actually sort of considered getting two Rottweiler puppies but am supremely satisfied with just my female Rottweiler Amalia.

Another couple actually got a male and a female, but dangers lurk behind doing this.

However, there’s a potential monkey wrench in your best-laid plans.

If you choose two sibling puppies, then you could face challenges due to littermate syndrome.

Littermate syndrome describes the phenomenon when two puppies from the same litter grow up together in the same home.

The puppies get so attached to each other and form such a deep bond, it can spark behavioral issues.

Unfortunately, it can also prevent your puppies from bonding with you, leaving you feeling a little bummed to say the least.

Is Littermate Syndrome Real?

While not an exacting scientific or medical diagnosis, the concept of littermate syndrome is very real.

However, that doesn’t mean it’s necessarily a given situation for all sibling pups that you raise together.

As with many things, multiple factors can influence the probability and severity of littermate syndrome.

But, there has been quite a bit of evidence suggesting it best to avoid sibling dogs.

In fact, in some cases, even unrelated puppies adopted at the same time can exhibit signs of littermate syndrome.

Three Beagle puppies sitting in a basket. Little rascals might develop littermate syndrome if taken home together.
Photo by Jarun Ontakrai on Shutterstock

Therefore, if you want more than one puppy, you risk dealing with several behavioral problems.

The theory is that you adopt puppies during a critical time in their development, around 8 weeks.

This time is the age when puppies can start to leave their mother.

During this crucial time, littermates possess a deep bond to each other, recognizing each other by scent.

When puppies share this strong bond, it discourages them from interacting with their human family.

This lack of interest or interaction inhibits their ability to start understanding canine-human communication.

It can also influence how your dogs react and interact with other dogs.

A lack of socialization caused by disinterest in the environment and perhaps other dogs can potentially lead to behavioral issues as well.

What Age Does Littermate Syndrome Start?

Typically, puppies stay together with their mother until at least 8 weeks.

Between 8 and 12 weeks is when most breeders deem it okay for pups to leave the nest.

If you adopt two puppies around this time and raise them together, you could see signs of littermate syndrome as early as 8 to 10 weeks if puppies stay together after leaving their mothers.

However, slightly older puppies still less than 6 months of age that are raised together can also experience littermate syndrome.

So, basically, issues can begin as soon as young pups leave their mom but stay with each other, whether it’s 8 weeks or 6 months.

What Are the Symptoms of Littermate Syndrome?

If you’ve adopted two puppies from the same litter, you might start noticing some concerning behaviors.

For example, your pups might whine or bark frequently, seem overly fearful or anxious in new situations, and be challenging to train.

You might also notice your new furry family members paying little to no attention to you.

All these can also be caused by a variety of other (non-concerning) factors or a lack of a proper training program.

Be on the alert for clues the dogs might show through their interactions (or lack thereof) with humans.

Also, take particular note of how the two dogs behave when they are apart and when other dogs are around.

Here are a few possible symptoms of littermate syndrome:

  • The dogs show fear or anxiety toward new people, experiences, and other dogs.
  • Puppies display extreme separation anxiety when they’re away from each other. Potential signs can be excessive barking, whining, pacing, and destructive behavior.
  • The dogs only eat when they are together.
  • You might notice a lack of focus and difficulty with things like training because the dogs distract each other constantly.
  • The puppies only seem to want to play with you if they are together.
  • The dogs might fight with each other or show aggression towards other dogs.

Always take a holistic approach and evaluate all the criteria one after one and check if they could be caused by something totally different.

How Common Is Littermate Syndrome?

Although littermate syndrome is not a guarantee, it’s a fairly common occurrence when you adopt puppies the same age.

In addition, some believe that certain breeds are more prone to littermate syndrome than others.

However, there are no evidence-based studies to back up these claims.

Overall, professionals recommend avoiding adopting puppies younger than 6 months old at the same time.

However, it’s best to be prepared to put certain steps into practice if you insist on doing so.

You’ll need to stay dedicated and consistent if you want to try and avoid littermate syndrome.

Does Littermate Syndrome Always Happen?

In a nutshell, no, littermate syndrome doesn’t always happen. However, a lot depends on environmental factors and how you raise the puppies.

If you don’t make a point to treat them individually, then the likelihood of littermate syndrome increases significantly.

A lot also depends on how soon you start working toward preventing littermate syndrome.

How to Prevent Littermate Syndrome?

Of course, the best way to try and prevent littermate syndrome altogether is to adopt dogs of different ages.

For example, you could adopt a puppy but then select an older dog for your second pup.

Another option that could also be successful is to adopt your dogs at least six months apart.

When you stagger your timeline for bringing home your new pups, your dogs are more apt to bond with you.

Plus, it’s a lot easier for you to focus on helping one dog get acclimated at a time to their new environment.

This idea is a good practice no matter your dogs’ age.

However, whether you choose one of these options or move forward with adopting littermates, it’s essential to socialize your puppies properly.

It’s also vital to start your action plan right away; the longer you delay, the more likely littermate syndrome will develop.

Furthermore, it’s critical to treat your dogs as individuals, making a point to spend time with them separately.

Not only does this one-on-one time help ease the effects of littermate syndrome, but it also helps you bond with your dog.

Can Littermate Syndrome Be Cured?

If your dogs are already exhibiting signs of littermate syndrome, all is not for naught.

It will take a lot of dedication, but yes, it is possible to remedy the situation. However, immediate action is best.

The sooner you can start working on a plan to resolve the various issues, the better.

Separating your dogs for training is a significant part of this plan so that you can work with them individually.

Remember, it’s about each dog feeling comfortable and confident in their own skin and with their human family.

However, if your pups already share a strong bond, you may need to ease into the separation gradually.

Again, if you plan to adopt two puppies simultaneously, it’s best to prevent littermate syndrome from occurring in the first place.

Employing the following techniques can potentially help ease existing signs of littermate syndrome.

  • Crate your dogs separately, leaving the crates side-by-side at first and then gradually moving them apart. Eventually, the ideal situation would be to have the crates in entirely different rooms. 
  • Train your dogs separately as well. Plan out a training schedule where you only work with one pup at a time. If you plan to enroll in obedience classes, do two separate classes on occasion.
  • Work on socializing each dog independently; take your dog to public settings, go on a walk, and enjoy some play sessions. Then, repeat the same activities with your other pup.
  • As your dogs start to become more independent, you can gradually ease them into joint activities. Enlist the help of another family member or friend. For example, if you plan to take both dogs on a walk, you handle one and your friend the other.
  • Even as you start to have joint training and play sessions, still maintain individual sessions with each dog as well.

Do Dogs Outgrow Littermate Syndrome?

Without a thoughtful and constructive action plan to remedy behavioral issues, it’s improbable your dogs will simply outgrow littermate syndrome.

If you want to be able to get the situation under control, it’ll be because you’ve allowed them to develop independently and receive proper socialization, not because they’ve outgrown anything.

Besides, training one puppy is hard enough – trust me, I know. Puppy blues times two incoming.

As with anything when it comes to your pets, if you’re concerned about their well-being, talk with your vet.

Have you already adopted two puppy siblings and are experiencing some challenges?

I’d love to hear from you in the comments. If you’ve dealt with littermate syndrome in the past, what are some things that helped you and your pups?

Disclaimer: This blog post does not substitute veterinary attention and does not intend to do so. I am not a veterinarian or pet nutritionist. If your dog shows any sign of illness, call your vet.

About Danielle

I am the founder of PawLeaks where I share weekly tips on dog training and behavior. Sharing a passion for dogs and helping owners to solve problems through understanding canine behavior and modification is my number one goal.


Sunday 15th of January 2023

I have two GSD male and female 9 months old, you can't quite tell where one starts and the other one ends. We're working on slowly separating them. Our male isn't too bad but our female is horrendous of your on a joint walk and the male is a head with my partner she will pull me over to get back to him. If you try putting them in separate rooms she will bark and wine and continuisly attack the door to get to him. She is petrified of other dogs and he his more than happy to play with them.


Saturday 10th of December 2022

Hi Danielle, This is a unique situation. I got a male Golden Retriever from a very reputable breeder when he was 8 weeks old. The breeder kept two males from this litter, with the plan of ultimately placing one of them depending on which one showed better conformation. Now they are 4 months old, and she has probably selected the one she will be keeping. I am thinking about taking the other one when he is 5-6 months old. He is already house trained and knows basic (and some advanced) commands, as does my boy. Do I need to worry about littermate syndrome, or is it likely to be a non-issue since they are older? They do play together sometimes for a couple of hours, and have stayed together for a couple of weeks, with no issues. Thank you.


Tuesday 13th of December 2022

Hi Barb, if you keep these tips in mind and the pups get along with each other well, there's probably nothing to worry about. Since there's such a time difference between when the first vs second pup is added, you just have to make sure that it will work between them.


Wednesday 9th of November 2022

I'm considering adopting 2 chihuahua littermates.

I totally understand all the things to do to prevent littermate syndrome, and I have had many dogs in the past, so it all makes sense.

My question (that I can not find the answer anywhere) is how long is the process of getting past the potential of developing littermate syndrome. I'm committed to dealing with the preventative measures (crates, training, walking, socializing, bonding) independently, but how long does this process take?

At some point, I would like them to be able to go on walks it just observing them to know when they're confident in meeting people and remembering their training even when they're together? Am I looking at 6 weeks of teaching independence or is forever?

Lots of sites explain the how, but not the how long.


Thanks, Joe


Thursday 10th of November 2022

Hi Joe, there's no set time frame but you definitely shouldn't worry about it forever. It can take as little as 4-8 weeks to build a solid foundation. Even beyond that, constant training will be required but that definitely does not mean that you won't be able to on walks together etc. Some individuals experience a lot fewer problems.

Personally, I advise people against getting littermates, especially if it's an intense breed. If you want to adopt, it might be even harder since they've already formed certain habits but of course, you might feel like they have a playmate and besides, rescuing both is better than just one.


Wednesday 19th of October 2022

Hi Danielle, I have two Labrador siblings - they are nearly 4 months now and sleep in separate crates in separate rooms at night, we feed them in their crates too so that they are fed separately (with a door shut between the two rooms as one of them inhales their food and finishes before the other!), my husband takes them for their main morning walk separately one after the other (the one left behind doesn't seem to fuss at all), then I take them for a small joint walk on my lunch break. I also alternate which one I take to puppy class each week, and again, the one left behind doesn't fuss whilst the other is away, they just sleep as it's in the evening.

They are lovely dogs, have different personalities and have definitely bonded with us - we enjoy lots of cuddles with them and also lots of licking! When do we need to stop worrying about the risk of Littermate Syndrome? It would be nice to think that eventually they can have normal open dog beds around the house that they can share when they are older (if they want to). From what you have written it looks like the risk reduces from 6 months onwards maybe or do we need to wait until we are through adolescence?

Thanks in advance!


Wednesday 19th of October 2022

Hi Kathryn, the fact that your pups seem to do well if the other one's away is a good sign. It's hard to say what the risk is and when it's going to be safe but I wouldn't worry too much about it if your dogs are doing fine. Prevention is essential and sounds like you're setting them up in a way that they won't experience many issues.

Keep in mind that bonding time is important too. Playing together, sleeping together, going on walks together.

While some people feed dogs separately their whole lives, I'd say it's definitely possible for two pups to eat in the same room. One just needs to be taught not to touch the other's food if they're finished earlier. You can just distract them, reward for not trying to get the other one's food, etc. When it comes to sleeping, it's up to you but since they're pretty young, potty accidents might be an issue right now. Once that training is solid and you've established a routine, it's probably okay to let them sleep freely. Every dog is different though and I know some people keep their crates longer than others but it really depends how your dogs react.

Cheers, Danielle


Friday 19th of August 2022

We adopted 2 male labrador littermates. Currently 8 1/2 weeks old. I've followed the breeder for years and she is awesome as far as we know. She always has a waitlist for her dogs. I asked he about getting 2 together and she said she had more than a dozen families do this and no problems. I was more worried about bonding with us verses each other - I had not heard of littermate syndrome. Then I heard about it and now I am worried. We have 2 sons ages 10 and 13 and we thought it would be great to get 2 at the same time. We also have a 14 year old lab. We are active people. Averaging 5-7 miles of hiking for the adults each day - kids join us for 1-3 miles depending on other activities. We already have the puppies sleeping in two separate rooms at night. They have 2 crates that we have them in during the day. We plan to train them separately. having them eat in their crates separately. They do play fight and it does get rough but I'm limiting that now and they're responding well. Any chance we make it out of this without littermate syndrome? ANY suggestions? I can't barely seem to find success stories.


Saturday 20th of August 2022

Hi Megan, it's always best to know about this beforehand but even if you don't, chances are slim that something will go wrong just because you got littermates. If you look out for a few things, train them and avoid separation anxiety, it should go well. You're probably not taking them with you yet, but it's important to state that 5-7 miles is great for adult dogs (as well as humans), but it's not for puppies. I actually have an article on how to safely exercise pups.

It's good to occasionally train separately and get them used to not having the other one in their face 24/7, but you're probably fine to let them sleep in the same room (especially if it's in your room). It's also no issue if the eat at the same time, but it's best if they have separate bowls. However, that's just small details and it's up to you how you want to do it. Play between them is great, that's why people get littermates after all :).

Cheers, Danielle