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Littermate Syndrome – Should I get 2 littermates?

Is it a good idea to get 2 puppies of the same age together? Read our article to find out.
March 4, 2026 by
Littermate Syndrome – Should I get 2 littermates?
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You’ve found a puppy that you love and you go to the breeder’s facility. You see another puppy from the same litter, and you fall in love with that too! You end up buying 2 puppies from the same litter because it’s pretty hard to resist, isn’t it?

You actually think that it’s a great idea since they will have each other, they will never be bored and they will learn together.

This scenario is not far from the reality.

A lot of people out there decide to get 2 littermates for the reasons stated above.

Is that a wise decision though?

Let’s discover that together.

WHAT IS THE LITTERMATE SYNDROME

Littermate Syndrome is a term that dog professionals use to describe a series of behavioural issues that can develop to puppies from the same litter or even unrelated puppies of same or very similar age that are raised together in the same household.

It occurs when the puppies form a hyper-attachment to each other prohibiting them from functioning independently and forming a bond with their humans.

More specifically, the puppies become so dependent on each other that they struggle to develop social skills with other people and animals making them prone to serious behavioural issues such as fear, insecurity, anxiety and even aggression.

It’s also important to note that the term “littermate syndrome” is not an official medical diagnosis but an informal term used by dog trainers & behaviourists.

SIGNS OF LITTERMATE SYNDROME

If you are thinking of getting 2 puppies of the same age or even if you already have them in your family, it’s crucial to be able to know and recognise the signs of this “condition”.

  • Training Difficulties
    Puppies will struggle focusing on the humans and follow obedience cues which makes the training challenging.
  • Anxiety when separated from each other
  • They tend to panic when they are separated from each other and they usually show that by whining, crying and become extremely distressed. That always goes away when they are back together.
  • Hesitancy meeting new people, dogs & experiences
    Due to their co-dependency, puppies do not have the confidence to happily meet new people or experience new things outside of their comfort zone.
  • Bully-type behaviour towards each other
    You might see bully-type behaviour from one of them which will take the form of constant pinning and intimidation in a lot of interactions between them. You may also see possessive behaviours such as guarding resources (toys, food, resting spaces) or behaviours such as pushing the other dog away to gain human’s attention
  • Rough play that can escalate quickly
    Even though rough play can be part of their development and it’s common that dogs that live together can be a bit rough to each other, when we are talking about littermate syndrome, the play becomes too intense that can often lead to fights.
  • If the play time does not include regular pauses, role reversals (the one chasing becomes the one that being chased), or when you see one dog constantly trying to escape, pinning the other dog on the ground without allowing for escape, please be aware that these can lead to conflict and potential fighting.

puppy littermates

WHY LITTERMATE SYNDROME CAN BE A PROBLEM

Littermates (or puppies close to age raised together) can develop a lot of behavioural issues that need immediate action.

You need to keep in mind that it will be difficult for them to stay apart which will be a problem when you might want to get one to the vet or the groomer. It will also affect any training that you may want to do as in most cases, training 2 dogs means that they need to be trained separately and then pair them together.

They will also struggle focusing on you and follow instructions or cues which can lead to frustration and disappointment.

If you ever want to visit a new place or environment, they can appear hesitant or fearful which means that they won’t enjoy it as they will be highly stressed.

Lead problems might also occur as they tend to be more reactive, especially if they are anxious and stressed when they experience something new or meet new people or other dogs.

Due to their lack of confidence, they can also get unsure and potentially aggressive towards other dogs or people.

HOW TO PREVENT LITTERMATE SYNDROME

If you still want to get 2 puppies of the same age in to your home or if you have already done this, it’s essential to learn how to prevent this condition from developing.

The good news is that not all puppies of the same age being raised together will develop littermate syndrome but being proactive is always better than being reactive.

Here are some tips to follow:

  1. Feed them separately, on different bowls and away from each other.
    This should prevent or minimize the risk of resource guarding or competing about food.
  2. Walk them individually at least 80% of the time with the rest 20% to be relaxed walks together.
    The 80/20 split is ideal if you want to build focus with each puppy separately.
  3. Have separate training and play sessions.
    This helps with learning to control their impulses and encourage focus to you.
  4. Have separate crates or beds ideally with a barrier in between so they can’t see each other.
    This teaches them to self-sooth without each other’s presence.
  5. Socialize them as individuals.
    This way, they will learn to be resilient and face new experiences with confidence instead of relying to each other’s presence.
  6. Practice alone training by letting each of them stay on their own for a couple of hours.
  7. This is crucial as it helps preventing separation anxiety issues and encourage independence
In case you already face serious behavioural issues (such as aggression between the dogs), you need to seek professional help by consulting a dog/vet behaviourist. As this type of aggression can become nasty and put both dogs’ health and welfare in danger, a lot of dog owners take the decision to rehome one of the dogs.

Littermate Syndrome might or might not happen when getting 2 puppies from the same litter or 2 unrelated puppies of very similar age but all dog professionals would advise you against it.

If however, you still want to 2 or more littermates it’s essential to be able to recognise it and prevent it.

Knowledge, understanding and prevention makes all the difference in raising confident, emotionally balanced dogs.

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