Littermate Syndrome: Why One Isn’t The Loneliest Number

By Chelsea Hunt-Rivera / May 21, 2018
Littermate syndrome

Most people aren’t brave enough to adopt two six-week-old puppies. However, when you’re standing at the adoption agency, holding those two balls of adorable fluff, the thought may pop into your mind that maybe two would be easier than one? After all, they are siblings. They obviously love each other. They are all one another knows. How hard could two puppies be? (Spoiler alert– incredibly hard)

The truth of the matter is many animal behavioralists, dog trainers, and individuals who know what they are talking about, strongly urge against adopting siblings. The suggestion does not come from an opinion that raising a puppy is a lot of work (it is), but rather in order to avoid the phenomenon that has been coined, Littermate Syndrome.

sibling puppies for adoption

What is Littermate Syndrome?

Littermate syndrome is a condition that involves the behavioral issues and developmental challenges. The syndrome emerges when siblings are adopted together and the deep primal bond shared between them inhibits the puppies from being able to understand the world around them or form a connection with their owner.

Littermate syndrome doesn’t happen in every pair of litter mates who are adopted and raised under the same roof. However, when it does occur, the issues can be incredibly stressful for a new dog owner. That being said, it happens often enough that experts advise against bringing home a sibling pair, no matter how adorable they are.

Signs of Littermate Syndrome

signs of littermate syndrome

No two dogs or two pairs of dogs are exactly alike. You may adopt siblings and never experience what we are about to discuss. However, if you do end up adopting a puppy pair, it is important to be on the lookout for the typical signs of littermate syndrome, including:

Fear of Strangers

Unless your new puppies have been through trauma that would explain a massive fear of other dogs or humans, it is pretty uncommon for pups to be afraid. Puppies tend to be very curious and go up to just about any person or dog for a quick sniff.

An unexplainable fear of strangers (humans and other dogs) and the behavior associated with the fear are common signs of littermate syndrome.

Severe Anxiety with Separation

High levels of anxiety when one puppy is separated from the other is a tell-tale sign of littermate syndrome. Even if the pup is only apart from their sibling for a short amount of time, it will appear that the world is ending.

The puppies are so bonded with each other that their owner nor another dog will be able to help with the separation anxiety. The only relief comes when the siblings are reunited.

Fear of New Stimuli

Another common sign of littermate syndrome is noticing that your puppies seem to be afraid of virtually anything unfamiliar. Any new sensory experience may cause the pups to cower in fear. This includes sensory experiences such as different noises or a friendly touch. It may seem as though the only way the pups are comfortable is alone with each other.

Difficulty Learning Basic Obedience

Raising one puppy is hard work. From tireless nights to coming home to find your couch in pieces, a puppy is a full-time commitment.

When raising two puppies (who are not related or littermates), the work doubles and the sleep gets halved.

Therefore, you can see how raising littermates can be near impossible. With the puppies constantly distracting each other, on top of being so closely bonded with one another, proves to make training the pups a trying time for any owner.

Even the most basic obedience commands become a struggle as the siblings view the experience as playtime. Training littermates together can also lead to additional socialization and behavior issues in the future because everything that they have ever experienced has been with each other.

Problems Associated with Littermate Syndrome

aggression issues in dogs

Unfortunately, the aforementioned issues are primarily the first signs that new puppy owners may see, but they aren’t the only indications of littermate syndrome. Some behavior issues may last the entirety of the dog’s life.

Aggression Issues

A huge issue that arises when raising littermates is constant aggression between the pair. We know that we just finished telling you about how the puppies have an unbreakable, primal bond are more or less obsessed with each other. However, that’s only one possible scenario.

Once they grow out of the puppy stage, many owners report non-stop fighting between the dogs.

Studies show that aggression and bullying are much more common between siblings than it is between dogs who are not related.

Furthermore, the aggression can get severe, often causing the rehoming of one of the dogs to be necessary.

Emotional Dependence

We discussed the severe anxiety that litter mates often face when separated, even for short periods of time. We should also mention that the separation anxiety can continue throughout the dogs’ lives.

The unhealthy emotional dependence that the dogs have on one another also proves to affect how their behavior with other dogs, regardless of age. Dogs with littermate syndrome have difficulty interacting with puppies, adolescent dogs, and adult dogs.

Double Trouble – Double the Costs

Raising one dog isn’t cheap. Raising littermates is downright expensive. From food, to training, to vet bills, all costs double when raising two dogs. Additionally, it may prove to be even more expensive raising littermates due to the behavior challenges that may cause the need for more training.

Littermate Syndrome: What You Can Do

dog crates

If you find yourself reading this article and thinking “welp, I’m screwed,” don’t panic. Again, not all siblings will develop littermate syndrome. Furthermore, there are ways to prevent it if you’re already brought home a pair.

The end goal of the prevention methods we are about to discuss is to avoid the pups from developing a total emotional dependency on one another.

Separate Creates

Experts advise dog owners to separate the puppies in different crates at night. At first, the crates can be near each other, but gradually owner should move the crates further away. This will allow the puppy to know that even though they are alone, they are still safe.

Additionally, experts encourage owners to keep the crates in a bedroom at night so that the puppies can be in close contact with their human family members.

Different Training Sessions

We discussed how difficult training littermates can prove to be. Training the pups separately will allow you to have their undivided attention without the potential distraction of their playmate sibling.

Additionally, training the pups separately will also teach each puppy to look to you for cues and commands and not each other.

Separate Play Time

Furthermore, dog behavior specialists urge pet owners to arrange separate play time with other dogs. Separate play time will allow each puppy to grow into their own, individual personality through socialization.

Many owners believe that because the dogs have each other, they don’t need to socialize with other dogs. However, this just isn’t the case. In fact, if littermates only socialize with their sibling, it greatly adds to their behavior issues and anxiety when apart. Separate play time will help avoid the puppies from developing an unhealthy emotional dependency on one another.

These tactics are also in an effort to avoid the severe separation anxiety that littermates so commonly have. Avoiding separation anxiety is possible if the pups feel comfortable on their own from the start.

Littermate Syndrome: The Bottom Line

littermate syndrome the bottom line

Again, we cannot stress enough that littermate syndrome is not a definite conclusion when adopting siblings. Experts believe that genetics play a role in developing the syndrome. However, perhaps the most important factor in whether pups develop littermate syndrome is the commitment level of the dog owner.  If you chose to adopt siblings, make sure you are ready for everything that comes with it. While those two balls of fluff are adorable right now, they will quickly grow into dogs who will each have their own, individual needs.

Therefore, a good general rule of thumb to follow is adopting one pup at a time. If you are planning on bringing a puppy into your life, first do your homework. Adopt a pup that makes sense with your living environment and lifestyle and put all of your focus in training that one puppy. Later down the line, you may want to consider adding another dog to your family, which is totally fine and healthy!

At the end of the day, pet owners should not only want what is best for their pup, but also recognize what is best for themselves. Littermate syndrome is an exhausting situation that you will potentially have to deal with forever. Avoiding it only makes sense for all parties involved.


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How to fix Littermate Syndrome?

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Littermate Syndrome: Are 2 Puppies Better Than 1? Think Twice.



About the author

Chelsea Hunt-Rivera

Chelsea Rivera is a Dedicated Pet Parent who loves to create amazing content for pet owners and is helping change pet wellness as the Head of Content for