March 19, 2023

Littermate Syndrome

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What To Do When Your Puppies Have Littermate Syndrome 

What Is It, How To Address It, And Why It’s Not The End Of The World.

There’s nothing quite like bringing a new puppy into your household - except maybe bringing in two puppies! That’s definitely a line you’ll hear from someone who’s trying to convince you to purchase a second dog.

On paper it seems like an excellent idea! After all it can be a scary transition for a pup to go from their mom and littermates to a new household with new sights, smells, and people too. 

Having one of their siblings by their side can help them feel more comfortable during this big change, right? 

These owners believe the dogs will be able to entertain one another while you and the family aren’t around. 

You already have to purchase toys and water bowls and leashes, so it's not such a huge deal to double up on some of these items.

Unfortunately, we have to break it to you that while it sounds good in theory, adopting two puppies from the same litter can present some unique behavioral and training problems in your dogs as they grow.

These issues are known as Littermate Syndrome. 

Littermate Syndrome is when the puppies have bonded so closely together it actually impedes their individual ability to learn about the nuances of human and canine interaction and grow into independent mature dogs. 

As littermate syndrome dogs grow they don’t see the world properly and are unable to cope with new stimuli and stressful situations.

Many dog professionals from trainers to shelters and breeders are actively discouraging new pet owners from adopting siblings and some are refusing to place siblings in the same home for this very reason.

What is Littermate Syndrome?

As described above, Littermate Syndrome (also known as littermate aggression or sibling syndrome)  is when siblings from the same litter bond so closely that it makes bonding with their humans and other animals much harder. 

When puppies have littermate syndrome they often become fearful around other humans and dogs. If you separate two sibling dogs with littermate syndrome they’ll grow anxious or even aggressive. 

This is due to the hyper-attachment they’ve formed with each other.

Littermate syndrome makes training dogs so difficult because they don’t respond positively to anyone other than their sibling,

As a behavioral issue littermate syndrome can vary in severity. 

There is no guarantee sibling dogs in the same household will exhibit signs of littermate syndrome, but there is definitely a risk if precautions aren’t taken.

If you do end up adopting multiple littermates, be on the lookout for any signs of it developing so you can address them immediately. 

It’s one of the more serious behavioral issues and can affect both your dogs for their entire lifespan. If not managed, littermate syndrome can lead to needing to rehome one or both of your dogs so they can receive the proper care and attention.

Signs of Littermate Syndrome

The following behaviors are signs that your dogs may be developing littermate syndrome:


Codependency is when dogs react to new stimuli or stresses by growing difficult or avoidant in their presence. Codependency in dogs is dangerous because if one of the siblings passes away the surviving dog is emotionally devastated and can’t properly cope.

Separation Anxiety

Separation anxiety can really affect your dog’s emotional state. On the more severe end it can prevent them from going anyway by themselves without having a breakdown.

Fear Of People & Dogs

Because dogs with littermate syndrome are codependent it prevents them from exploring the world and engaging with new situations and stimuli. When they begin to encounter new people and dogs it can trigger fear within them.

Poor Social Skills

Puppies with littermate syndrome spend so much time with each other they don’t learn how to interact with other dogs. They often communicate in their own language and it prevents them from becoming friends with other dogs.

Usually in these pairings one of the dogs is dominant and the other is submissive. When you put the dominant of the two in a group of other dogs at a dog park it can become a dangerous situation fast.

The sooner you can begin socializing your dogs to play nice with others the better.

Difficulty To Train

Training one puppy by itself can be challenging, training two with codependency is even harder. They already have short attention spans and having a sibling there can provide for an even bigger distraction. 

Sibling Rivalry

Sibling rivalries among dogs with littermate syndrome isn’t common, but it does occur. When dogs are young the rivalry seems cute and harmless but as they get older it can become quite serious for both dogs. In these cases owners will have to separate the pair sometimes in different homes to protect the submissive sibling. 

If your puppies are showing signs of littermate syndrome there’s a lot you can do to lessen its effects and improve their behavior over time with training techniques.

As soon as you bring your puppies home, you can begin taking preventative measures against littermate syndrome. 

Early Warning Signs Of Littermate Syndrome

If your dogs are showing you any of the above behaviors, it’s likely they have developed littermate syndrome. 

From here it’s not impossible to change their behaviors, but it is much easier to prevent codependency from forming even before it starts.

Here are some early warning signs that your dogs might be forming a hyper-attachment. 

Remember, this is for dogs who are 3-6 months old.

Seeking comfort together when facing new people and dogs.

If they avoid situations with new people or dogs and stay within close contact with one another. This is an early warning sign of codependency.

Distress when separated.

If your dogs whimper, whine, pace around, and otherwise show signs of stress. This is indicative of separate anxiety forming.

Difficulty learning basic commands.

If they fail to learn basic commands like sit, down, and stay. The hyper-attachment formed by littermate syndrome dogs makes it hard to focus them during training sessions thus their ability to learn is impaired.

Fighting Between siblings

If the siblings fight frequently and begin to show signs of an imbalanced power dynamic. This can lead to aggressiveness as your dogs grow if the power dynamic isn’t corrected.

Overall anything that doesn’t seem like normal puppy development should set your littermate syndrome radar off.

Addressing Littermate Syndrome In Your Puppies

If you have committed to raising siblings together, be prepared for the challenge. 

Raising one puppy can be difficult enough, and raising a second at the same time isn’t just twice as difficult, it’s closer to ten times as difficult. 

But if you are serious about it, and want to give both dogs the best chance possible at developing into mature independent dogs, then we will give you all the best techniques possible to ameliorate the effects of littermate syndrome.

The best thing you can do for your puppies is to separate them as much as possible throughout their daily routines.

This allows them to form attachments with other people and animals and decreases their reliance on one another. 

If you allow them to spend too much time together a hyper-attachment may form.

Alone, they will have no choice but to become independent, and with your guidance, competent and then confident as they grow in their puppyhood.

The ultimate goal is for your dogs to be able to live together and have a great dynamic between each other as well as with you and your family. It’s only by separating them for the time being that we can later reunite them as healthy independent canines.

Separating Your Puppies

Breaking down your daily routines to accommodate two puppies separately is a significant challenge. It’s best if you can enlist family members, friends, and dog professions to assist you throughout the challenge.

Separate Walks

Start walking your dogs separately. You can begin by walking them together but with different handlers. This allows you and the other handler to experiment with walking further apart and heading in different directions briefly. Watch how they react at different distances. If they react with anxiety, begin a training plan to ease them moving in and out of sight with each other. 

Over time this will acclimate your dogs into having independent experiences in the world without having the other to lean on. 

Socialize Separately

Work on socializing each dog on their own. Take them on outings to dog parks and public places. Expose them to as many stimuli and types of people as possible. Get them used to cars, trucks, adults, children, dogs, cats, birds, bikes, and the area around your home. This goes a long way to creating an independent dog later in life.

Separate Crates

Stop crating your dogs together! Get a second crate asap and start creating separation between your dogs. You can start by leaving the crate next to one another in order to ease any separate anxiety they may be experiencing, but as they get used to the separate kennels you can begin moving them further apart. 

Go slow and if they are experiencing too much anxiety, slow down your process. As they grow comfortable, progress to moving the crates to opposite sides of the same room and then to separate rooms in your home. 

While they are crated separately in the same room they’ll still be able to see, hear, and smell one another but they won’t be able to be in physical contact. This will decrease the codependency they are forming and begin to allow them to act independent.

Separate Training Sessions

Separating them at training time is of crucial importance because your puppies have to learn to look to you for direction instead of the other sibling. You want each of your dogs to feel the strongest bond with you instead of one another. If you are bringing your dogs to obedience classes it’s best to enroll them in separate sessions.

Separate Feeding

Start feeding your dogs separately. This means separate dishes for food and water. As you continue to work on their anxiety levels, move the dishes into separate rooms.

Remaining Apart At Home

Keep your dogs separated when you are all at home going about your daily business. They should be comfortable spending hours apart self-entertaining. Try to make their alone time as enjoyable as possible. Give them a toy like a Kong with a treat inside to keep them active and busy for a while.

This will distract them from thoughts of their sibling while they work for a tasty reward.

Stick To Your Plan

We did warn you that dealing with Littermate Syndrome was no easy task and it’s serious enough that it needs to be addressed immediately. It’s not just a simple behavioral issue, it’s your dog’s social development on the line.

The longer you wait in dealing with littermate syndrome the harder it is to reduce the attachments they’ve developed and allow them to socialize normally.

Every week that goes by makes it that much harder so please don’t delay in forming your plan.

Establishing Independence & Reuniting Your Dogs

As your dog's progress through their training they will begin to establish their own independent personalities. You should see major changes in each dog’s behavior from the time you began addressing their littermate syndrome. They shouldn’t feel anxious engaging in daily activities alone and should be comfortable not seeing their sibling throughout the day. 

It’s now time to reunite your dogs! 

You can start doing activities with both siblings together again. Take them on walks together, playdates, to the dog park! Remember to reward them for their good behavior when playing nicely together. Life with your puppies will be a breeze compared to the gauntlet of raising them separately.

Final Thoughts

Successfully raising two sibling dogs is quite a task. Life is already stressful enough without having to carefully manage your pet’s lives. If you’ve taken on this challenge kudos to you, you’ve proven yourself to be an incredible caretaker of your dogs and you’ve likely learned a ton in the process.

If you’re considering adopting siblings and this blog has changed your mind, that’s perfectly okay too. Many breeders won’t even place siblings together because most owners aren’t experienced enough to avoid the pitfalls of raising siblings. If you really have your heart set on owning two dogs right now, then it may be best to just adopt one and wait six months until you adopt the second. This will allow you enough time to properly socialize your first dog and avoid the littermate training protocol.

However, if you are planning to move forward with siblings then we hope this article has given you a starting framework to conduct your training. We’re here to provide you with further professional assistance in creating a happy home for you and your dogs.

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