Littermate Syndrome: The Hidden Risks of Raising Puppy Pairs

As a dog trainer and a guardian of littermates who are , I am slipping into some amount of specialisation in Littermate syndrome, working with Littermates all over the US. Doing this has taught me a lot about the issue, what people see and experience with their dogs, allowing me to explore the problem across breeds & families – which shows me that Littermate syndrome is not only real, but a problem more and more families are experiences.

Let’s dive into this a little, let’s discuss what I’ve seen directly with the dogs I live with, and then the overall observations of working with littermate syndroms.

My situation: Lucy & Shelby

I have two step-dogs, Lucy & Shelby. Mr Rebarkable raised them and did a wonderful job given the adversity he faced. However, what he didn’t see coming was Littermate Syndrome.

I always thought Littermate syndrome was a myth, just a label used to describe inadequacy or similar – but I can say certainly it’s not. So when I became a part of Shelby and Lucy’s family, I suddenly started seeing the severity of their behavior. It took me a little while because I wasn’t familiar with their breed either (coonhounds are certainly unique), and it took me a while to make sure I was coming to the right conclusion. But they particularly struggled with;

Lack of tolerance for eachother – this resulted in a lot of fighting.

Lack of social skills – They don’t really understand how other dogs communicate, so adding in my own dog (Indie) it became a learning experience for all involved.

Resource guarding – particularly spaces for our girls.

Imbalanced/intolerant play – one would instigate play but it would escalate so quickly from bounce to aggression.

bringing home littermates can sound like an awesome idea. But whether it’s two, or three? It may not be a great plan.

What is Littermate Syndrome?

Littermate syndrome is a term we use to encapsulate a number of different symptoms (if you will), littermate syndrome is typified by a limited ability to develop normal social skills, independence, and often results in what I refer to as a lack of “individuality” – which I understand is a very human concept, but I do feel applies in this instance.

Littermate syndrome is not limited to puppies who are from the same litter, in fact it can apply up to an age difference of around 18 months from different litters.

Littermate syndrome occurs when two young puppies spend the majority of their time together, becoming overly dependent on each other for comfort, play, and interaction. This prevents them from forming normal relationships with humans. It also deprives them of important learning experiences as individuals.

Specifically, littermates that are constantly together tend to overly bond with each other, unable to function independently. They become distressed when separated, even briefly. This dysfunctional relationship makes training difficult and causes the puppies to miss crucial life lessons. As a result, the puppies may struggle to interact with people and other dogs in a healthy manner as adult dogs.

The term “littermate syndrome” is used to describe the inter-dependency, anxiety, and stress that develops when littermates are raised in the same household beyond the normal 8-10 weeks of age. It is not an official medical diagnosis but rather a behavioral condition coined by breeders, trainers, and owners. Recognizing and preventing littermate syndrome early on is key to raising happy, well-adjusted canine companions.

Causes of Littermate Syndrome

Littermate syndrome occurs due to the strong bond that develops between sibling puppies. Dogs are social animals, so having another dog from the same litter to bond with satisfies their need for companionship.

The pups rely on each other for play, comfort, and security. As a result, their bond to each other is prioritized over their relationships with people. This makes training and socialization much more challenging.

Since the puppies can fulfil their needs for social interaction with one another, they do not learn to look to their human owners to provide the same fulfilment. Their loyalty lies with their sibling rather than their human caregivers. This damages the human-canine connection that is so crucial for training and living harmoniously together.

Without proper socialization and training, the dogs can develop extreme anxiety when separated from each other. They can also become fearful or aggressive towards other dogs and people, because they did not form strong bonds outside of their sibling during the critical socialization period.

Littermate syndrome can often start with rough play.

Symptoms of Littermate Syndrome

Littermate syndrome can manifest in several concerning behaviors in puppies who are overly bonded to each other. Some of the most common symptoms include:

Anxiety when separated – Littermates who are too bonded will often display signs of anxiety and stress when they are separated from each other, even for short periods of time. They may whine, bark excessively, pace, or even have accidents.

Fighting – Littermates may become aggressive or reactive towards each other as they compete for resources like food, toys, and human attention. This can lead to fighting between the puppies.

Lack Of Social Skills – Social skills are formed with siblings initially, but when our dogs begin to ignore signs from others it makes them quite rude to other dogs.

Obsessive behaviors – Littermates can become so focused on each other that they display obsessive behaviors including constantly seeking out and pawing at each other. They may also shadow each other’s movements constantly.

Training and learning challenges – Littermates who are too attached often struggle to focus on training and learning because they are so distracted by each other. It disrupts the human-puppy bonding process.

Recognizing symptoms early on and proactively addressing littermate syndrome through proper training and separation can help prevent long-term issues. Close supervision, socialization, and scheduled one-on-one time are key.

Long Term Effects

Some of the long term effects of littermate syndrome include:

Fighting with siblings

Inability to relax

Excessive stress

Strong jealousy

Resource guarding

Poor intraspecies social skills

Inability to be left alone without experiencing severe distress, anxiety, barking, howling, destruction, and elimination issues.

Attachment to the sibling to an unhealthy degree. The adult dog may follow the sibling constantly, become aggressive toward other dogs that approach the sibling, and be unwilling to eat, play, or interact when separated.

Higher likelihood of being surrendered or returned to a shelter due to inability to live happily as a single dog.

The intense bond formed so young creates an inability to cope with normal life events. Simple things like vet visits, grooming, travel, or a sibling’s absence can cause extreme distress well into adulthood. Littermate syndrome has lifelong impacts that often require intensive treatment to manage. Preventing littermate syndrome through proper early socialization and separation is critical for a dog’s long-term wellbeing.

It’s often a case that two females together will find it harder to overcome littermate syndrome


The best way to prevent littermate syndrome is to avoid adopting sibling puppies. If you already have littermates, take steps to prevent bonding issues.

Separate the puppies. Give them their own crates, training times, walks, etc. Don’t let them sleep together. Rotate joint playtime and alone time.

Separate spaces for feeding. Eating together is stressful in multi-dog homes, let alone when the other dog is your littermate. Seperating them at this time is one of the easiest ways to remove sibling pressure.

Train the puppies as individuals Work on training each puppy individually every day. Have separate obedience classes, walking routes, etc. Note: this extends to remembering that what works for one puppy may not work for the other(s).

Give individual attention. Make sure each puppy gets one-on-one time with family members. Take them on solo trips to bond.

Socialize separately. Introduce each puppy to new people, dogs, places, etc. on their own. Don’t rely on their sibling for confidence.

Use staggered schedules. Feed, walk and play with puppies at different times. Prevent competition and enable independence.

Allow privacy. Ensure each puppy has their own private space for meals, rest and play. Don’t force interactions.

Supervise play. Monitor play sessions to prevent bullying or obsessive bonding behavior. Keep things positive!

Advocate generously. Usually one pup tends to be more of a space invader, or lack boundaries, and so familiarising yourself with the body language and communication signals will allow you o intervene and redirect the space invader pup, and give your other dog space.

Rehome if needed. If prevention isn’t working, rehoming one puppy may be kindest. Littermate syndrome can be severe.

Overall you can see here that we’re trying to teach the puppies individually, giving each puppy the space to form who they are, and to experience the world without forming strong associations with having their sibling as part of who they are.

Risk Factors

Certain types of dog pairings are much more likely to develop littermate syndrome than others. The highest risk is seen when:

Puppies from the same litter are adopted together. Being from the same litter means they are the same age and likely have very similar personalities and temperaments. This makes bonding to each other easier than bonding to their new owner.

Same sex pairings, particularly females, have a higher chance of developing littermate syndrome and for that littermate syndrome to become aggressive.

Puppies of similar age are adopted together. Even if not from the same litter.

The most at-risk scenario is two sibling puppies of the same sex and age being adopted into the same home. Guardians should use extreme caution with this pairing to prevent littermate syndrome from developing. Monitoring the pups closely and employing early intervention is key.

Behavioral adjustment process for littermate syndrome.

The most effective treatment for littermate syndrome is to separate the dogs as much as possible so they can develop their independence. This means:

Feeding, walking, training, and playing with the dogs individually instead of together. Make sure each dog gets adequate one-on-one time. For us, this looks like having certain dogs in the room at certain points of the day, only having both sisters in together when everyone is fulfilled. And they’re always supervised.

Using crates, pens, doors or baby gates to physically separate the dogs for periods throughout the day. Start with small increments of alone time and gradually increase.

Plenty of opportunity for decompression activities. Decompression allows them to de-stress and prevents things like trigger stacking.

Praise appropriate play. It sounds simple, but praising appropriate play and stopping it before it goes wild will show your pups that the cycle they may know isn’t always true.

Remove boundaries/frustration enducing events. For example, a common one is making a dog wait at a door, or before they eat, but it adds in frustration that results in minimal benefit. So we found it very effective to remove these things.

Giving each dog their own space, toys, bed, food/water bowls etc. Don’t allow sharing of high-value items.

Taking the dogs on separate outings, car rides, walks. Bring one dog at a time on errands.

Attending training classes or socialization sessions individually. This helps each dog gain confidence without relying on their sibling.

Sleeping in seperate spaces was really pivotal for us. We tried crates with a pony wall between them – but separate rooms had the best result.

Desensitising and counter conditioning certain learned behaviors or environments. For example, we’re still in the process of desensitising doorways and moving together.

Considering rehoming one of the puppies if the above methods don’t improve the issues. Littermate syndrome can be very difficult to manage long-term in the same household.

Medication may be recommended by your vet in severe cases, such as anxiety medication to reduce stress when separated. But medication only treats the symptoms – the root cause is the over-attachment, so separation techniques are essential. Be patient and consistent, it can take months of effort but is worthwhile to raise happy, well-adjusted dogs.

In fighting between siblings is one of the pinnacles of littermate syndrome – and it’s terrifying for those in the home.

Training Tips

Littermate syndrome can be prevented and managed through proper training techniques. The key is early and frequent separation of the puppies. Here are some tips:

Crate train each puppy separately. Get two crates right away and crate train each puppy individually. They should sleep in separate crates at night and also spend time crated alone during the day. This prevents over-bonding and teaches them to be comfortable alone.

Walk the puppies separately. Take each puppy on individual walks, training sessions, and socialization outings. Do not walk them together all the time. This prevents pack behavior and teaches them to bond with their human more than each other.

Train as individuals. Enroll each puppy in their own training classes. If you work on training at home, do separate sessions with each puppy rather than together. This helps establish you as the leader rather than having the puppies only look to each other.

Give individual attention. Make sure each puppy gets one-on-one time with family members. Interact, play, and cuddle with each pup individually so they don’t become overly dependent on their sibling for affection and attention.

Frequent and long-term separation is key. It may seem excessive at first, but it helps prevent irreversible littermate syndrome behaviors from developing. With patience and consistency, you can raise happy, well-adjusted puppies.

Rehoming Considerations

If littermate syndrome has already developed in your dogs, rehoming one or both dogs may be necessary for their well-being. This can be an extremely difficult decision, but it’s important to prioritize the dogs’ health.

Gradual separation is key if rehoming is pursued. Start by separating the dogs for short periods of time with you or another family member. Slowly increase the duration of separation while monitoring the dogs’ stress levels. Signs of stress include panting, pacing, whining, loss of appetite and more. Keep sessions positive and lighthearted, and make sure the dogs get one-on-one time with their people.

As separation sessions increase, begin exposing the dogs to new environments and people on their own. This will help ease the transition if one dog is rehomed. Finding an experienced owner who understands littermate syndrome is ideal. Shelters often have foster programs where dogs can adjust before being adopted.

While heartbreaking, rehoming in littermate syndrome can give dogs the opportunity to develop independence. With proper precautions, the dogs can go on to lead happy, healthy lives. The key is making the transition gradual while ensuring each dog gets the individual attention they need.

peace can be achieved, but it’s not easy.

Long Term Outlook

The long-term outlook for dogs with littermate syndrome depends greatly on how it is managed from a young age. With proper treatment and training, many dogs can overcome the worst behavioral effects of littermate syndrome. However, it does require diligent management and separation of the sibling dogs over their lifetime.

The prognosis is best when littermate syndrome is identified early and the puppies are separated before the behaviors become ingrained. However, even dogs that have developed entrenched littermate syndrome behaviors can show improvement over time with training. The key is to be consistent with enforcing boundaries and providing individualized socialization and training. It will likely be an ongoing process throughout the dogs’ lives.

With dedicated treatment, most dogs can learn to behave independently, interact normally with their owners, and get along with other dogs. However, they may always be more socially underdeveloped compared to dogs that did not experience littermate syndrome. Their bond with littermates often remains very strong, so they may never relate to other dogs in a truly normal way.

Lifelong management is needed to prevent regression. Owners must remain vigilant about separating the sibling dogs periodically, and not allowing unhealthy co-dependence to recur. With consistency, patience, proper training and maturity, dogs with littermate syndrome can often live relatively normal lives. However, it does require dedicated effort on the owner’s part. The long-term outlook is generally positive, especially when caught and addressed early.

How Are Shelby & Lucy Doing?

Like a lot of things in dog training, we take a couple of steps forward, and a couple of steps back! But that’s ok. Overall, the hounds are better than they have ever been, and the littermate syndrome is well handled. We’ve eliminated the fighting, we’re having more and more quiet, calm time together, and all in all, the hounds relationship is improving.

Which is all I need!

Do You Need Help With Littermate Syndrome?

Whether it’s prevention or cure, fighting littermate syndrome alone is really hard and its so confusing too, because there is pretty much zero data around. But as a trainer, I can say I have a lot of experience in living with this, and have helped littermate siblings all over the world with a lot of success in creating harmonious homes.

If you need help, get in touch. I offer online training for clients around the world and can help you make the changes you want to see!

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