Do you know that roughly 1.6 million dogs are adopted each year in the US? Are you considering getting more than one pup? Have you heard about littermate syndrome? 

If you’re planning to adopt a furry pal, you should be prepared. We’ve got you covered. 

Most shelters recommend against getting two puppies at the same time. But what’s wrong with that?

Adopting sibling dogs or wanting another friend for your pup seems like a great idea in theory, but it comes with significant risk. When two or more dogs come from the same litter or are in the same age bracket, they can struggle with littermate syndrome.

In this article, you’ll learn everything about it:

Let’s jump right in.

What Is Littermate Syndrome?

Experts also call it littermate aggression or sibling syndrome. It’s associated with behavioral issues between littermates adopted in the same home after reaching the age of ten weeks. 

When puppies turn three months old, most shelters separate the litter by placing them in new homes. It gives the little ones enough room to mature physically, learn how to play, and adopt essential behaviors, such as self-grooming. Besides, that pushes them to explore things outside their comfort zone created by their mother and siblings. 

What Are the Signs of Littermate Syndrome?

Puppies that stay in the same household after crossing the 3-month mark can develop incredibly codependent relationships with their siblings, alienating them from the outside world. 

So adoption can be challenging. But you can do more than a few things to make your pup sleep through the night.

Here are some traits of littermate syndrome in dogs to look out for.


One of the leading behavioral problems caused by littermate syndrome in dogs is codependency. Whenever your furry friend faces a new or stressful stimulus, it’ll pull back and avoid dealing with it. 

It gets worse if one of the puppies dies, as the surviving codependent dog would be devastated emotionally. 

Separation Anxiety 

Separation anxiety follows the codependency stage. It can be so severe that the dogs might not want to go for a walk separately. Or at least not without emotional meltdowns. 

We have some tips on preventing littermate syndrome below. 

Impact on Social Skills

When two puppies grow up together, you’d think they’d be amazing at socializing. But that’s not the case. 

If they learn to play with each other and don’t get exposed to other dogs, they tend to communicate in their very own language. This closed-off interaction prevents them from bonding with other dogs. 

When you see littermate syndrome symptoms, know that the two dogs aren’t equal in social standing. One is always more submissive towards the other. When the dominant pup tries entering the pack at the local dog park, all hell breaks loose. 

Fear of People and Other Dogs

Codependency prevents the puppies from exploring and understanding their surroundings. When a specific situation, thing, or person is unfamiliar to them, that can spark fear. 

Their instinct tells them to get away from the situation and go back to the comfort of the dog they grew up with. 

Training a puppy when it’s seven weeks old is crucial. The sooner you start, the better. 

Difficult to Train

Training a puppy when it’s seven weeks old is crucial. The sooner you start, the better. 

But teaching two or more dogs at once can be challenging, especially if they show littermate syndrome symptoms. Since they have each other to keep them company, their attention spans are short. 

Training dogs isn’t easy and requires extra hours. Also, you have to be careful if they’re siblings so that each learns how to deal with situations on its own. Remember, codependency is the root cause of all behavioral issues related to littermate syndrome. 

Sibling Rivalry

Littermate syndrome aggression isn’t a common trait, but it’s a serious one. 

It can happen with same-sex siblings when the dominant dog bullies the submissive one. When they’re younger, rivalry seems like fun and games, but it can get dangerous later on.

The owners have to separate the dogs and, in some cases, rehome one of them to protect the other. 

How to Prevent Littermate Syndrome?

Raising two puppies at once doesn’t necessarily mean they’ll struggle with littermate syndrome. With your help, they can grow up to be well-adjusted and independent. 

In any case, there are a few things to consider if you have littermates. When dealing with two siblings, the keyword is ‘separately.’

Your pets should be equal but do everything apart, so you’ll need two puppy checklists. Take care to separate the furry balls in:

  • Playing 
  • Crates
  • Eating
  • Training
  • Taking them to the vet
  • Visiting the dog park 
  • Going on a walk 

The idea is to have your pups live in the same house but teach them how to do things without each other. Doing so will ensure you raise two well-adjusted and confident dogs that can thrive together and succeed separately. 

With all this going on, the right food may be the last thing on your mind but it’s vital. Check out some of our favorite puppy foods here.

What to Do if Your Dogs Have Littermate Syndrome?

Don’t worry. There’s a lot you can do to fix it. If you’re dealing with problems other than severe aggression, you have to focus on two things — discipline and separation. 

Keep the dogs apart and work on building their independence and confidence. Here are some steps you can take to help you cope with littermate syndrome in dogs.

Dealing with Separation Anxiety

That’s the first issue you’d want to target. You cannot possibly work with your dogs if they freak out at the thought of being separated. 

The best way of correcting that is by applying slow desensitization. For starters, you’ll need to buy two crates to keep your pups separate. Avoid putting them in two different rooms. It’ll cause too much trauma to your dogs. Go about it slowly. First, put the crates next to each other so both dogs can touch and smell the other with a barrier between them. 

Keep the sibling puppies in their crates separately for 30–60 minutes. Once this period is over, try to place them further away. If you see any signs of worry, return the crates where they were. 

Teach your dogs that it’s fun to be away from one another. Play with each dog separately by giving them their favorite toy or treats. Remember, dogs learn with positive reinforcements. You can even add some cbd treats to calm them down and ease the process.

Separate Training Sessions

Once the dogs are ok being apart, you can move on to training them separately. It may take a long time for your dogs to get used to that, so don’t worry about the timeline. Have patience and keep pushing them to learn on their own.

The third step is to help dog siblings establish their independence.


The third step is to help dog siblings establish their independence. Having individual personalities and doing everyday things without their bestie is vital for teaching them how to deal with the world on their own.


Your dogs can see each other once they finish training and learn how to be independent. Reunite them by engaging the siblings in shared activities, such as trips to the dog park and obedience lessons. 

You can take them out to socialize with other cute fur balls on dog dates. If they’re on their good behavior, give them treats to show your appreciation. Just make sure you know how much to feed your dog.

Final Thoughts

Raising two dogs with our busy schedules and everyday stress is a challenge. You can easily ignore small signs of the littermate syndrome that can accumulate and turn into a much bigger issue in the future. 

Unless you’re truly ready to take the responsibility of raising two puppies at once, we recommend you adopt only one. Littermate syndrome can be a distressing problem for dog owners if they don’t take proper precautions. If you can’t deal with it on your own, consult a vet or a professional trainer

Good luck on your journey of raising furry siblings!

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