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Littermate Syndrome in Dogs: 9 Vet-Reviewed Facts

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By Nicole Cosgrove

Dog Littermate Syndrome

Vet approved

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Reviewed & Fact-Checked By

Dr. Lauren Demos

DVM (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

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When you’re adopting a puppy, it’s tempting to pick up one of their littermates. They’re just so darn cute together and you don’t want to separate them. But while it can be tempting, most experts recommend not adopting puppies together. That’s because if you adopt puppies together, they’re far more likely to suffer from littermate syndrome.

But what exactly is littermate syndrome, what can you do about it, and how do you prevent it in the first place? We’ll answer all those questions and more for you below.

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The 9 Facts About Littermate Syndrome in Dogs

1. Littermate Syndrome Presents With Hyper Attachment

two puppies at the park
Image Credit: Eric Carlander, Shutterstock

If you have two puppies exhibiting behaviors associated with littermate syndrome, they’re very likely to get extremely attached to each other. This extreme attachment is what can create so many other problems since the dogs focus so much on each other instead of figuring out human interactions.

Puppies need time to figure out how to interact with people, and if they focus on each other too much, they won’t learn what they need to.

2. Dogs With Littermate Syndrome Are Anti-Social and Fearful

Littermate syndrome occurs when your puppies don’t take the time to properly learn and understand human interactions, which leads to confusion. When your puppies are confused, it can quickly scare them.

Scared puppies tend to shy away from social situations, which can make them aggressive if you try to force them into an interaction.

3. Littermate Syndrome Can Lead to More Fighting

dogs fighting
Image Credit: RugliG, Shutterstock

While littermate syndrome often leads to puppies that are extremely close to each other, it can also end up with puppies that fight far more often with each other than they should.

This is because they’re trying to figure out their social hierarchy, leading to a lot of natural competition. It’s more likely that puppies of similar size and age will display this behavior, making it more common for littermates.

4. It Can Lead to Severe Separation Anxiety

Because puppies with littermate syndrome become very accustomed to having someone or another dog with them, if you leave them alone, they can display severe separation anxiety. Proper socializing early on can help with this, but it requires more work than it would with a single puppy.

5. You Can Manage Littermate Syndrome

English springer spaniel and Boxer puppies playing_NewnardHouse_shutterstock
Credit: NewnardHouse, Shutterstock

While it’s far more work to adopt littermates together, it is possible to manage littermate syndrome and reach your dog’s full potential. However, it requires far more work to simultaneously socialize two puppies.

You need to meet the needs of both puppies, and this includes giving them time away from each other so they can learn to properly socialize with people and not just their littermate.

6. Dogs With Littermate Syndrome Should Spend Some Time Apart

Dogs with littermate syndrome want to spend all their time with their littermate. But while this might be what they want to do, if you want them to reach their full potential, they need to spend some time apart.

If they’re already displaying signs of littermate syndrome, you need to be careful with this process. Ease them into time apart. Otherwise, you might stress them out too much and create even more behavioral problems.

7. It’s Best to Adopt Dogs at Least 6 Months Apart

Labrador retriever puppies sitting on grass
Image By: sobaka777, Shutterstock

While you can manage littermate syndrome, it’s really best to avoid the situation entirely. To avoid littermate syndrome, you should adopt puppies at least 6 months apart from each other. This gives the first puppy plenty of time to interact with people and learn how they should act before adding another puppy.

And when you do add a new puppy, they’ll already know how to act, and they can help teach the new puppy how to act around people. Avoiding littermate syndrome is pretty easy: just don’t adopt two puppies together!

8. Non-Sibling Puppies Can Develop Littermate Syndrome

While it’s more common for puppies from the same litter to develop littermate syndrome, even if you adopt two puppies at the same time from separate litters, it’s still possible! It’s all about the puppies connecting and bonding with each other instead of with people.

If the puppy doesn’t focus on people, it won’t develop the necessary social skills, which can lead to littermate syndrome. It really doesn’t matter if they came from the same litter.

9. Littermate Syndrome Makes It Harder to Train Your Dog

Image Credit: rock-the-stock, Shutterstock

While littermate syndrome isn’t a physical detriment to your dog, it is a behavioral problem. It will make it much harder to train your dog to do just about anything. From basic necessities to advanced tricks, littermate syndrome makes it harder.

In fact, if your pup has littermate syndrome, it’s best to try and treat that before moving on to any advanced training.

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While littermate syndrome isn’t a foregone conclusion if you adopt puppies together, it is a possibility you should be aware of. And now that you know a little more about it, you can avoid it or put in the necessary work to mitigate some of the worst symptoms.

It can be a bit frustrating, but with enough time and work, you can properly socialize two dogs from the same litter if that’s what you want to do!

Featured Image Credit: Anna Krivitskaya, Shutterstock

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