What is littermate syndrome in dogs and why should you be aware of it? In this article, we’re going to explore this less-known condition, find out what are the symptoms of littermate syndrome, and share with you the best tips on raising sibling puppies successfully. Let’s dive in!

Littermate Syndrome Dogs

If you’ve decided to get a puppy, it might seem like a good idea to adopt two at the same time. After all, they’ll have someone to play with and both of them will get to socialize with another dog. Plus, you won’t have to go through the exhausting period of puppyhood twice. You’ll be spending less time and energy on training and socializing while getting double the fun and cuteness. 

Unfortunately, it’s not as easy as it seems. Adopting two puppies who are the same age or even from the same litter can prove to be a great struggle. Although not all puppies develop littermate syndrome, it’s an important issue to keep in mind before you adopt two puppies at the same time. 

What Is Littermate Syndrome In Dogs?

Littermate syndrome a.k.a. sibling syndrome in dogs refers to a variety of canine behavioral problems that arise when two puppies, often siblings, are adopted at the same time. Littermate syndrome is a condition where two puppies who live together form a very strong bond that interferes with their normal behavior and social development. 

With littermate syndrome, puppies form a so-called hyper-attachment, where their whole focus is on each other. To put it simply, two puppies will form a stronger bond with each other than their human parents. If not treated properly, it can lead to a whole set of behavioral problems that will challenge your relationship and your dogs’ wellbeing.

Although the term suggests that littermate syndrome only affects siblings, that’s not the case. Puppies who are the same age and have been adopted at the same time can just as well develop an unhealthy codependency towards each other. 

So, is littermate syndrome real? Sibling syndrome or littermate syndrome in dogs isn’t a medically recognized condition, but more of a behavioral issue that’s been observed by veterinary professionals and dog owners alike. Although it’s not a ‘proven’ condition or diagnosis, it’s still an important behavioral issue that you should deal with as soon as you notice any of the symptoms we mention below. 

Additionally, there’s no way to pinpoint how common is littermate syndrome, because not all sibling puppies experience littermate syndrome. Nevertheless, it is a valid concern to keep in mind when expanding your family. 

Do Dogs Recognize Their Siblings?

Many dog owners know the urge to find out what happened to the other puppies from the same litter. It’s not uncommon for pet parents to organize a little get-together for littermates once they’re adults. However, we can never know for sure if littermates recognize each other later on in life. It is possible that a dog can recognize its family even years after being separated from the litter. Some owners witness a magical reunion of two long-lost siblings who are over the moon to see each other. Other pups react to their littermates just as they would while encountering any dog. 

With littermate syndrome, it’s not so much about the fact that dogs recognize each other, but more about their proximity to one another. That’s supported by the fact that sibling syndrome can develop even when the puppies aren’t from the same litter. 

What Age Does Littermate Syndrome Start?

Breeders and shelters usually recommend separating puppies from their litters by the time they’re 3 months old. For the first 8 weeks, a new puppy has to spend time with its mama and siblings to learn essential social and behavioral skills. Now, it may seem that the longer puppies stay with their littermates, the better they’ll develop and learn how to socialize. However, it can lead to the exact opposite. The longer puppies are raised together, the higher the risk of developing an unhealthy bond between the littermates. 

Littermate syndrome usually starts to present itself when puppies are raised together beyond the 10-12 week mark. It’s not known when exactly puppies develop littermate syndrome. But based on the observed behavioral patterns, it’s safe to say that separating puppies from the litters by 2-3 months of age is a good pointer to follow.   

Symptoms of Littermate Syndrome

So, how can you recognize the signs of littermate syndrome? Are there any indicators to look for? Even though there’s no way to know for sure whether or not puppies will experience littermate syndrome, it’s serious enough to give it some consideration. Let’s take a closer look at the commonly observed symptoms of littermate syndrome. 


One of the first signs of littermate syndrome to look for is your puppy becoming shy, timid, and fearful. Even puppies who are otherwise outgoing and social by nature can become shy when dealing with sibling syndrome. This often leads to fear, anxiety, and stress when they’re exposed to new people, dogs, situations, and even smells. As dogs with littermate syndrome develop a severe codependency, they rely on the other puppy for comfort when experiencing fear of the unknown or unfamiliar. 

Separation Anxiety

It should be no surprise that dogs who have a codependent relationship also struggle with separation anxiety. This is similar to separation anxiety that some dogs experience when they’re away from their human parents. In this case, littermate syndrome causes dogs to attach to each other, instead of the owner. 

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If one or more puppies have developed separation anxiety, they might struggle with even the easiest of everyday tasks when the other dog is not present. It’s not uncommon that puppies don’t want to eat alone, neither play with toys or people without the other pup. In severe cases of separation anxiety, dogs might become fearful, panicky, or even destructive without their buddy. 

Having said this, it’s completely normal if a puppy whines and cries right after you bring them home. After all, it’s a huge life change having to adjust to a whole new home and family. But with lots of love and attention, you’ll notice that your little furbaby will feel better in no time. 

Problems With Obedience

Another common symptom of littermate syndrome is difficulty learning new skills, obedience, and acceptable behavior. And no, it doesn’t just apply to advanced commands and tricks. Puppies with littermate syndrome often struggle with basic obedience skills. Training one puppy is hard enough, but when you add another baby to the mix and spice things up with littermate syndrome, things can become very tricky. 

As we mentioned earlier, littermate syndrome leads to puppies developing a severe attachment, where their focus is on each other, not the owner. Naturally, this will make training your puppies a much more difficult task, as they’re constantly distracted by one another. 

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Sibling Aggression

In more serious cases of littermate syndrome, some dogs may become aggressive towards their siblings. It’s especially common in same-sex siblings or same-sex puppies who are the same age. Over time, the aggression can intensify and become very dangerous once dogs reach maturity. 

Challenges of Littermate Syndrome

Littermate syndrome presents itself through various behavioral issues that can be difficult to manage. Not only does it require more time and effort on your part, it negatively affects a dog’s development and overall life quality. 

Due to the severe attachment they share, dogs with littermate syndrome often have a hard time letting anyone else into their small bubble. One of the reasons why many people consider adopting two puppies instead of one is that they’ll get to socialize with another dog. Even with littermate syndrome, two puppies can get along perfectly fine when it’s just them two. However, they might have serious difficulties when they’re exposed to other dogs. The same goes for human interactions. Puppies with littermate syndrome often experience stress and anxiety when meeting new people. While two puppies may know how to communicate within the family, learning how to socialize with other dogs and people is crucial for their development. 

Likewise, as puppies with littermate syndrome tend to become very attached to each other, it can also lead to difficulties bonding with their owners. What’s more, it can also cause problems even with basic training. As puppies with littermate syndrome are so fixated on each other, learning new skills can be very challenging. 

In addition to everyday struggles that dogs with littermate syndrome have to face, there’s also the added worry if and when the inevitable happens. There will be a time when one of the dogs dies, but if the two share an extremely strong bond, the surviving pup will have a very difficult time coping with the loss of their best friend and usual source of comfort. That’s why it’s especially important to provide a healthy and safe home environment where puppies can thrive as individuals. 

How Can We Reduce The Effects Of Littermate Syndrome?

It can be difficult figuring out how to fix littermate syndrome when puppies develop such a strong codependent relationship. If you’ve just started to notice early signs of littermate syndrome in young puppies, you’ll likely have an easier time adjusting them to a new routine. 

First and foremost, all puppies should get used to being alone. Similarly to separation anxiety, puppies with littermate syndrome can’t cope away from their main source of comfort – the other dog. To help your puppies get used to spending time on their own, we recommend you start with the training as soon as you bring them home. 

To set your pups up for success, you should be treating them both as equal individuals. They should learn how to go through the basic everyday tasks without the other one present. It’s equally important that they both learn how to enjoy spending time alone, so they won’t form an unhealthy attachment to company. 

To reduce the effects of littermate syndrome in dogs, you should provide both puppies separate time and space to go through their daily routine. The best way to do it is by separating the puppies during mealtimes, walkies, playtime, training, and sleeping. It may seem impossible to separate your dogs during these times of the day, but it will teach them both independence. To balance it all out, you should make sure both your puppies get to spend time together during the day as well. 

Additionally, an important part in raising a puppy is to let them meet new people, dogs, places, and situations. You might want to do this separately, if your puppies are still learning how to spend time away from each other. However, keep in mind that socialization and introducing new places and situations is integral for a dog’s development.

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How To Prevent Sibling Syndrome In Dogs?

Although many veterinary professionals like dog behaviorists and trainers advise against adopting two puppies at the same time, that’s not to say you’re doomed when adopting siblings. Remember, not all sibling puppies struggle with extreme attachment to each other. However, you’ll have to be prepared for even more rigorous training routines and extra time spent on both puppies separately.

The key to preventing sibling syndrome is by bringing up your puppies as two separate individuals. Don’t treat them as one dog in two bodies. Rather, let them both flourish as individuals and find their own way in this world. Call them each by their own name and let them both discover their own personality. 

If you’re committed to raising sibling puppies successfully, you should be prepared to:

  • Provide separate mealtimes for both puppies
  • Walk, play, and go to the dog park separately
  • Train them at separate times
  • Crate train them separately
  • Visit the vet or trainer separately
  • Spend separate one-on-one time with both puppies

Additionally, you might want to consult with a veterinary behaviorist or trainer who can help you figure out how to prevent littermate syndrome in your household. 

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Frequently Asked Questions About Littermate Syndrome In Dogs

How Common Is Littermate Syndrome?

Littermate syndrome isn’t a recognized medical condition and there’s insufficient scientific evidence to support it. Consequently, there isn’t much data about how common is littermate syndrome. It doesn’t affect all sibling puppies or puppies who were adopted at the same time. On the other hand, littermate syndrome in dogs is common enough, so you should be aware of it before you adopt two puppies at the same time. 

Can Littermate Syndrome Be Cured?

The bond that develops with littermate syndrome leads puppies to becoming extremely codependent. There’s no cure for and it can be very difficult to manage. However, with consistent training, it’s possible to reduce the symptoms of littermate syndrome.  

How Do You Break Littermate Syndrome?

The best way to reduce the risk of littermate syndrome is to avoid it altogether. However, we don’t recommend giving one of your dogs up for adoption just because they exhibit some signs of codependency. Rather, you should pay attention to your dogs’ behavior and take appropriate action as soon as possible. 

With littermate syndrome, the key is to teach the puppies how to spend time alone and how to not depend on the sibling in their everyday life. You can do this by gradually separating the puppies. You should feed, train, walk, and crate train your puppies at separate times or at separate locations. Provide them both plenty of opportunities to socialize with other dogs, new people, and visit new places without the other one being present. Treating two puppies as individuals will set them up for success later on in life.

Is It Bad To Get Two Dogs From The Same Litter?

The bond that develops with littermate syndrome leads puppies to becoming extremely codependent. That’s why breeders separate puppies from their litters around 10-12 weeks of age. Bringing up two puppies at once is not an easy task and requires a whole lot of time and energy. If you’re adamant about adopting two pups, make sure you have the time, energy, and patience to provide both puppies the attention they need. It’s probably going to be very time consuming, but it’s necessary to provide both puppies a healthy and fulfilled life. 

Is Littermate Syndrome Real?

Even though littermate syndrome isn’t a recognized medical condition, it’s widely observed by dog behaviorists, trainers, veterinary professionals, breeders, and dog owners. Littermate syndrome in dogs can lead to a wide set of behavioral issues that puppies start to exhibit when they form an unhealthy bond with their siblings or other puppies in the same household. Although littermate syndrome is obviously not as severe as a hereditary disease, it can still drastically affect your dogs’ and your own life quality. 

To conclude, all dog lovers know the temptation of adopting two puppies instead of one. It’s double the fun, double the cuteness, and a whole lot of love. Even better, you’ll be spending time and energy on training and socialization anyway, why not bring up two puppies at once! Unfortunately, not many people know that adopting two puppies can, in fact, do more harm than good. That’s not to say raising sibling puppies successfully won’t be possible. However, you’ll most likely be dealing with a whole new set of obstacles while having to maintain a strict and consistent routine. We hope this article managed to give you more insights into this less-known behavioral issue that many dogs and their owners struggle with. 

If you’d like to learn more about similar topics, make sure you check out all of our articles on behavioral and training

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