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Littermate Syndrome: Understanding the Potential Risks of Raising Siblings Together - PawSafe
Dog Behavior

Littermate Syndrome: Understanding the Potential Risks of Raising Siblings Together

Photo of Tamsin De La Harpe

Written by Tamsin De La Harpe

littermate syndrome

Littermate syndrome is a phenomenon that occurs when two puppies from the same litter are raised together and become overly dependent on each other. This can lead to a range of behavioral issues, including aggression towards other dogs, separation anxiety, and difficulty with training. While littermate syndrome is not a guaranteed outcome of raising two puppies together, it is a risk that should be taken seriously by anyone considering this option. 

Overall, while raising two puppies from the same litter can be a rewarding experience, it is important to be aware of the potential risks and to take steps to prevent littermate syndrome from developing. By being proactive and taking a thoughtful approach to puppy raising, such as by making sure they have their own calming doggy beds,  it is possible to raise happy, healthy dogs that are well-adjusted and well-behaved. To get some insight into this issue, we’ve consulted several expert sources on canine development.

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One of the main reasons that littermate syndrome can be problematic is that it can be difficult to identify until it has already taken hold. In many cases, the puppies may appear to be getting along well, playing and cuddling together, but over time they may become increasingly anxious and reactive when separated from each other. 

This can make it difficult to socialize them with other dogs and can lead to a range of behavioral problems that may be difficult to address. As such, it is important for anyone considering raising two puppies together to be aware of the risks and to have a plan in place for preventing littermate syndrome from developing.

In their book “Genetics and the Social Behavior of the Dog,” Scott and Fuller reported that when two littermates are raised together to biome guide dogs, one often fails where the other succeeds, even if they both did well in their early aptitude tests. They also found that puppies raised in homes where there are dogs not related to them don’t seem to show the same phenomenon.

They also believe that puppies raised in the same home with their mothers never go on to be  qualified guide dogs, leading to a lesser known syndrome called “apron strings syndrome” in dogs.

While there is no scientific evidence to prove the existence of littermate syndrome, many experts believe that raising two puppies from the same litter together can lead to behavioral issues, including separation anxiety, aggression, and fearfulness. To get a grip on what this syndrome really is, let’s look at several case studies.

Case Studies on Littermate Syndrome

Here are a few case studies that illustrate the challenges of dealing with Littermate Syndrome:

Case Study 1:

Two female German Shepherd puppies were adopted by a family. They were inseparable from the beginning and did everything together. However, as they grew older, they became increasingly aggressive towards each other. They would growl and snap at each other, and fights would break out frequently. The family tried to separate them, but they would become anxious and distressed when apart. Eventually, they had to give one of the puppies away to a new home in order to resolve the issue.

Case Study 2:

Two male Labrador Retriever puppies were adopted by a couple. They were very playful and energetic, but they also had a tendency to destroy things around the house. They would chew on furniture, shoes, and anything else they could get their teeth on. The couple tried to train them, but they seemed to be more interested in playing with each other than listening to their owners. Eventually, the couple had to hire a professional dog trainer to help them manage the puppies’ behavior.

Case Study 3:

Two female Beagle puppies were adopted by a family with young children. The puppies were very sweet and gentle, but they also had a lot of energy. They would run around the house and knock things over, and they would sometimes nip at the children’s heels when they were playing. The family tried to train them, but they found it difficult to keep up with their energy levels. Eventually, they had to hire a dog walker to take them on long walks every day to help burn off their excess energy.

These case studies illustrate the challenges of dealing with Littermate Syndrome. It can be difficult to manage the behavior of two puppies raised together, and it may require professional help to resolve the issue. It is important for potential dog owners to be aware of this phenomenon and to carefully consider whether they are prepared to deal with the challenges that may arise.

Understanding Littermate Syndrome

To understand what littermate syndrome is, we need to look at early puppy experiences and social interactions to see what may be causing abnormal behavior when we raise two puppies from the same litter together.

From a normal eight-week-old puppy’s perspective, being separated from their littermates and arriving in a new home can be a stressful and overwhelming experience. 

However, if they arrive with a sibling, they have a constant companion to rely on and feel safe with. This can lead to an exclusive bond forming between the two puppies, which can hinder their ability to bond with humans and other dogs.

 In other words, when littermates are never separated, their primary bond becomes with each other, rather than outsiders. They are each other’s main source of socialization. They are essentially raising each other and this is a problem.

In some cases, the bond between littermates can become unhealthy. One puppy may become dominant over the other, leading to resource guarding and increased aggression. Alternatively, both puppies may become anxious and insecure, constantly seeking validation and comfort from each other and growing suspicious or distant from other members in their household.

As the puppies grow older, their exclusive bond can cause further issues. They may struggle to interact with other dogs or become aggressive towards them, leading to difficulty in social situations. Additionally, they may struggle to form a healthy relationship with their human family, leading to hyper attachment (with each other), separation anxiety and other behavioral issues.

It is important to note that not all puppies raised together will develop Littermate Syndrome, and it is possible to prevent it through proper socialization and training. However, it is a risk that should be considered before bringing home littermates.

Causes of Littermate Syndrome

When two puppies are raised together from birth, they become each other’s primary source of socialization. This can be both positive or negative, depending on their relationship. 

1. Puppies are rivals and can bully each other

Puppies in litters are extremely competitive. Yes they do play with each other and form close bonds, but from the moment they are born they are fighting each other for access to a teat. As they get older, they may become competitive over the food bowl, or access to other resources like toys, their bed, or even their human. So when puppies from the same litter are kept together, they may keep developing this intense rivalry.

Also, if one puppy is dominant and bullies the other, the other may become more anxious and reactive, often taking to resource guarding. This often happens if you get one larger puppy and a “runt.” 

Also see:

Do dogs miss their puppies?

Do male dogs recognize their puppies?

Why doesn’t my dog listen to me?

2. Puppies from the same litter become each others primary bond

On the other hand, if they are closely bonded, then they may develop separation anxiety about being parted and may start to ignore humans or other dogs as their primary source of reward lies in constant interaction with each other. They learn to look to each other for comfort, fun, and interaction rather than the humans in their home. 

This can cause them to be distant towards anyone outside of their little ingroup. This is one reason that some human schools like to separate human twins in the classroom, as some people argue that twins can be prone to becoming codependent or not really forming a separate identity or sense of self without each other. 

This can be similar with puppies from the same litter that are never separated. Together since birth and spending every waking (and sleeping) moment together, they develop what we can call a codependent personality, where they just aren’t sure how to behave without each other, leading to problems learning.

 After all, most of what they are learning about how to behave is coming from the other. They are socializing mainly with each other and embedding behavioral traits in each other.

This is particularly true for the puppy with the “weaker” personality that may become very dependent on the more dominant puppy. This can explain why one puppy tends to fail at being a guide dog when raised with a littermate. 

This is incredibly complex and nuanced. This kind of psychological interdependence can still occur even if (perhaps especially) when one puppy bullies the other.

3. New Puppy Parents Don’t have enough time for both puppies

In today’s world, very few people have the time for one puppy, let alone two. This can lead to a lack of enough interaction to set clear boundaries and train correct behaviors, leading to more behavior problems.

4. Puppies develop at different speeds

It’s also important to remember that no two puppies are the same. An owner raising two puppies at once may develop a favorite that could learn faster and adapt better. This can quickly snowball into one “good” puppy and one “bad” puppy.

5. Littermates raised together may not be properly socialized with the outside world

Owners may neglect to socialize their puppies properly on the grounds that they can play with each other. This may leave them unsure how to behave in public and social environments, causing reactive or aggressive behavior.

6. Siblings raised  together hit puberty together

Dogs become adolescents together, meaning that they arrive at a place of hormones and boundary pushing at the same time. 

Ideally, when a dog becomes a teenager, they may have an older dog with a good temperament to help them learn boundaries (and a human that is consistent in helping their dogs navigate this phase). However, if they are at the same level of mental and emotional maturity and the same gender, they may quickly fall to bullying each other or rivalry or aggression.

Also see: 

Signs your dog needs to be neutered.

Finally, when two puppies are together all the time, they simply become each other’s primary bond. This is self-reinforcing in puppies that have a positive relationship because they are always open to playing with each other and having a positive interaction, which reinforces that bond that can cause them to ignore humans. 

On the other hand, if one puppy is more introverted and being bullied by the other, then you will likely see a spike in reactive and insecure behavior as they constantly battle over resources like food and toys.

Symptoms of Littermate Syndrome

Littermate Syndrome is a condition that can affect puppies from the same litter who are raised together. It is characterized by a range of behavioral and physical symptoms that can negatively impact the dogs’ wellbeing.

Behavioral Symptoms

The behavioral symptoms of Littermate Syndrome can include:

  • Separation anxiety when apart from each other;
  • Aggression towards other dogs or people;
  • Fearfulness or anxiety in new situations;
  • Difficulty with house training or obedience training; and
  • Overdependence on each other for comfort and security

These symptoms can be challenging to manage and may require professional training and behavior modification techniques to address.

Physical Symptoms

In addition to behavioral symptoms, Littermate Syndrome can also manifest in physical symptoms such as:

  • Poor immune system function;
  • Slow growth or developmental delays;
  • Malnutrition or poor nutrition due to competition for resources; and
  • Increased risk of genetic health problems due to inbreeding

It is important to note that not all puppies from the same litter raised together will develop Littermate Syndrome, and not all cases of Littermate Syndrome will exhibit all of these symptoms. However, recognizing and addressing any potential symptoms early on can help prevent more serious problems from developing.

Prevention of Littermate Syndrome

To prevent littermate syndrome, it is recommended to avoid adopting two puppies from the same litter. However, if the decision is made to adopt two puppies from the same litter, there are steps that can be taken to prevent littermate syndrome from developing.

  1. Provide individual attention and training sessions

    Firstly, it is important to provide each puppy with individual attention and training sessions. This will help prevent the puppies from becoming overly dependent on each other and develop their own unique personalities. Additionally, it is recommended to separate the puppies for short periods of time each day to prevent separation anxiety.

  2. Individually socialize each puppy with other dogs and people

    Secondly, it is important to socialize each puppy individually with other dogs and people. This will help prevent the puppies from becoming overly attached to each other and developing fear or aggression towards unfamiliar people or dogs. Do not take them together to training and socialization classes, or if your must, make sure a second person is handling one of the puppies.

  3. Provide each pup their own separate space

    Thirdly, it is recommended to provide each puppy with their own separate space, such as their own crate or bed. This will help prevent resource guarding and territorial behavior.

  4. Feed them separately

    Also make sure to feed them separately and avoid leaving them alone with high-value items they can fight about (see: can puppies chew bones?).

  5. Avoid them competing for your attention

    It is absolutely essential that puppies do not compete for your attention, as this will encourage them to start resource guarding you from each other.

  6. Prevent food aggression and competition

    It is important to provide each puppy with their own separate feeding and water bowls to prevent food aggression and competition.

  7. Their primary bond is with you and not each other

    Finally, when you have two puppies from the same litter, it is essential that their primary bond is with you and not each other. This takes a lot of extra time and work as you need to be interesting and build engagement with them. Instead of spending all day playing and bonding with each other, they need to have the best part of their day be when they are playing and bonding with you. During this time, you need to be actively building the confidence of the less dominant puppy, and gently shaping the more dominant one.

By following these preventative measures, the likelihood of littermate syndrome developing can be significantly reduced.

Treatment Options for Littermate Syndrome

Behavioral Modification

To overcome littermate syndrome, the pet parent needs to modify the behavior of the puppies. One of the most important things to do is to crate the puppies separately rather than together. This will help to reduce the bond between the puppies and encourage them to bond with their human parent.

Another important step is to engage the puppies in separate activities that will encourage them to be more interested in something other than each other. For example, playing fetch or swimming can be great activities for the puppies to enjoy.

To ensure that the puppies bond with the pet parent, it is essential to play with them individually and alone on a daily basis. This will help to build engagement with the pet parent rather than each other.

Professional Assistance

Professional assistance can be helpful in treating littermate syndrome. A professional dog trainer can provide guidance on how to modify the puppies’ behavior and help the pet parent to build a stronger bond with their puppies.

It is important to find a trainer who has experience in dealing with littermate syndrome. The trainer should be knowledgeable and able to provide clear guidance on how to modify the puppies’ behavior.

In some cases, it may be necessary to seek the assistance of a veterinary behaviorist. A veterinary behaviorist can provide a more in-depth assessment of the puppies’ behavior and develop a customized treatment plan to overcome littermate syndrome.

Overall, with the right treatment and guidance, it is possible to overcome littermate syndrome. It takes time and effort, but with patience and consistency, the bond between the pet parent and their puppies can be strengthened, and the puppies can learn to live happy and healthy lives.

Long-Term Effects of Littermate Syndrome

Littermate Syndrome can have long-term effects on the behavior and well-being of dogs. Here are some of the possible effects that can occur:

Separation Anxiety

Dogs with Littermate Syndrome may develop separation anxiety when separated from their littermate. This can lead to destructive behavior, excessive barking or whining, and other signs of distress.

Aggression

Littermate Syndrome can lead to aggression between littermates, as they may become overly dependent on each other and view other dogs as a threat. This can also lead to aggression towards humans, particularly if the dogs have not been properly socialized.

Fearfulness

Dogs with Littermate Syndrome may become overly fearful or anxious, particularly in new or unfamiliar situations. This can lead to avoidance behavior, such as hiding or cowering.

Lowered Trainability

Littermate Syndrome can make it more difficult to train dogs, as they may be more focused on each other than on their owner. This can lead to disobedience, as well as a lack of responsiveness to commands.

It is important to note that not all dogs with Littermate Syndrome will experience these long-term effects. However, it is important to be aware of the potential risks and to take steps to prevent or address any issues that may arise. This may include separating the dogs for training and socialization, providing individual attention and exercise, and working with a professional trainer or behaviorist.

Conclusion

In conclusion, littermate syndrome is a serious issue that can arise when two puppies from the same litter are raised together. While it is not a guaranteed outcome, it is important for owners to be aware of the potential risks and take steps to prevent it.

One of the most effective ways to prevent littermate syndrome is to raise each puppy separately. This means providing them with their own space, toys, and training sessions. It also means giving each puppy individual attention and socialization opportunities.

If raising the puppies separately is not possible, owners can still take steps to minimize the risk of littermate syndrome. This includes ensuring that each puppy has time away from their littermate, engaging in separate training sessions, and providing individual attention and socialization opportunities.

It is important to note that littermate syndrome is not a guaranteed outcome and many puppies raised together do not develop any issues. However, it is a risk that owners should be aware of and take steps to prevent. By providing each puppy with their own space, training, and socialization opportunities, owners can help ensure that their littermates grow up to be happy, healthy, and well-adjusted dogs.

Frequently Asked Questions

What are the signs of littermate syndrome?

Littermate syndrome is a condition that occurs when two puppies from the same litter become overly dependent on each other and have difficulty forming relationships with humans or other dogs. Signs of littermate syndrome can include fear or aggression towards other dogs or people, separation anxiety, and difficulty with training.

Is it bad to adopt 2 puppies from the same litter?

While it may seem like a good idea to adopt two puppies from the same litter, it can actually be detrimental to their development. Littermate syndrome can occur when two puppies are raised together, and it can lead to behavioral issues that are difficult to correct.

Can you fix littermate syndrome?

It is possible to correct littermate syndrome, but it requires a lot of time and effort. The puppies need to be separated and trained individually, and they may need to be socialized with other dogs and people to learn how to form healthy relationships.

How common is littermate syndrome?

Littermate syndrome is not a common condition, but it can occur when two puppies are raised together. It is more likely to occur in certain breeds that are prone to separation anxiety or have a strong bond with their littermates.

What breeds are prone to littermate syndrome?

Breeds that are prone to separation anxiety or have a strong bond with their littermates are more likely to develop littermate syndrome. Some of these breeds include the Weimaraner, Golden Retriever, and Labrador Retriever.

How to prevent littermate syndrome?

The best way to prevent littermate syndrome is to adopt puppies from different litters, or to adopt one puppy and wait a few months before adopting another. If you do decide to adopt two puppies from the same litter, it is important to separate them for training and socialization purposes.

Final Thoughts

In conclusion, littermate syndrome is a serious issue that can arise when adopting two puppies from the same litter. While it is not a guarantee that littermate syndrome will occur, it is important for potential adopters to be aware of the risks and take steps to prevent it.

One of the most effective ways to prevent littermate syndrome is to separate the puppies for significant periods of time each day. This can help them develop their own individual identities and prevent them from becoming overly dependent on each other.

Additionally, it is important for adopters to provide each puppy with their own separate training and socialization experiences. This can help them develop their own unique skills and personalities, and prevent them from becoming too reliant on each other.

Overall, while littermate syndrome can be a challenging issue to address, it is important for adopters to be aware of the risks and take steps to prevent it. By providing each puppy with their own individual experiences and identities, adopters can help ensure that their puppies grow up to be happy, healthy, and well-adjusted dogs.

Meet Your Experts

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Tamsin De La Harpe

Author

Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions. Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.

Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions. Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.