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Littermate Syndrome in Puppies

Updated: Jan 14


I get many people contacting me who have two puppies from the same breeder, from the same litter, and they want puppy training for them both.  After I explained the process of training two littermates, the new puppy owners realized it's always a lot more work than they ever expected. 

In this article, I will share some references that I found online and my own experiences with littermate syndrome, how to avoid it, and what to do if you can't and have to deal with it. The article that I'm referencing is from a website called, written by Jeff Stallings. A lot of people that he quoted in this article are reputable sources in the industry. 

Listen to the podcast episode on Puppy Talk.

What is Littermate Syndrome?

Litter Mate syndrome is a term that describes unwanted behaviors among sibling dogs, including aggression and intense attachment. It is often used to describe behavior issues that occur when two or more dogs from the same litter are raised together and adopted into the same home. (1)

What Are the Symptoms of Littermate Syndrome?

  1. Fearfulness of unfamiliar people, dogs, and other novel stimuli.

  2. Intense anxiety when separated even briefly, 

  3. Difficulty learning basic obedience skills and the fourth 

  4. Constant fighting with each other. 

  5. The puppies want to play with each other constantly.  They think that life is all about play and that there's no discipline, structure, obedience, or training.  They have no other interest in anything else. They can't even focus on anything else.

Dr. Ian Dunbar, who's a pet veterinarian and dog behaviors, says, “It's a disaster waiting to happen for the litter mates because they don't get socialized to other dogs or people, let alone to their owners.” He says, “When the puppies are five or six months old and meet an unfamiliar dog in a novel setting, they absolutely freak out.”

This is pretty accurate. Puppies that come from the same litter are often under-socialized because the owners think they've got each other. They don't need to be around other dogs. They don't even need to be around a lot of other people. They've got each other, and this is a big mistake when an owner has two puppies from the same litter. 

They have the mindset that they have a backyard, and the dogs can play in the backyard and in the house, and they never have to take the puppies anywhere because they've got this environment where they can play with each other all the time and get their needs met. This is an absolute disaster because they're never separated. They develop severe separation anxiety from each other and from their owners, and they can't function in life. 

Patricia McConnell is a dog trainer to dog trainers, and the author of one of the best books on dog training called The Other End of the Leash. Here's what she says about littermate syndrome: “They’re so busy playing with each other that you become the odd man out. It seems harder to get their attention, harder to teach them emotional control, and harder to teach them boundaries.” She says, “I have even seen some nasty cases of bullying and outright aggression between dogs of the same litter.” 

I found this information to be very accurate and authentic when I was called in to train two puppies from the same litter, and I really appreciate what Patricia McConnell has said in this article about the Litter Mate syndrome issue.

Nicole Wild, who has also written many books for dog trainers and on dog training, says, “People assume that having two same-age pups who play together and interact constantly covers their dog-to-dog socialization needs, but they in fact don't learn how other dogs play and have no idea about social skills with other puppies, adolescents, or adult dogs.”

How to Prevent Littermate Syndrome

  1. First of all, you have to have puppy training for them separately. You have one dog over in the crate, and the other dog is being trained for about 20 or 30 minutes, and then you switch them out. 

  2. Second thing, you take them for walks separately. This is going to help them learn to be apart from each other, to be civil while walking on a leash, and to have good leash manners. If you try to walk them together as young puppies, they will always play. This is not a good idea. 

  3. The next thing that you must do is once they've got all their vaccines, and they're able to be taken socially to places you want to take them individually with you, anywhere you can Pet Store, Home Depot, Tractor Supply Company, Lowe's, take them to work, take them for rides in the car, go through the drive-through. These are all socialization skills that each puppy needs to do independently. 

  4. The final thing that you're going to do is create a very clear structure and routine for them where they are doing things by themselves and not necessarily doing everything together. They're going to eat separately, sleep in separate crates, train separately, and go for walks separately. They're going to play with you separately, not each other. 

This is going to help the puppies learn that life is not all about playing with each other and that there are other components to life that they have to adapt to and that they have to deal with. This is the number one thing that I've seen go wrong when two owners get two puppies from the same litter: they don't separate them enough, and they're always together, and they can't control the puppies. 

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Listen to the podcast episode on Puppy Talk.


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