What is Littermate Syndrome

The term “Littermate Syndrome” is a little misleading because it isn’t a scientific phenomenon, but rather a set of behaviors we see as the result of puppies developing unhealthy relationships with other puppies. “Littermate Syndrome” can present itself in a variety of different ways, but it all comes down to the relationships formed during the critical socialization period in their development. During this stage of development puppies are still learning how to interact with other dogs as well as with people. When they aren’t taught how to appropriately socialize outside of the relationship they’ve already developed with the other puppy, they can develop a codependent relationship. 

Michelle from Inglenook Training Academy describes it as “going to a county where you don’t speak the language. Then you find someone who speaks your language. You’ll immediately bond with them far faster because of the ease of communication, possibly even to the point where you don’t try to learn the local language because it’s hard and you have a friend to translate for you. It isn’t the country’s fault you aren’t learning the language, or even your friend’s fault, but intentional effort needs to be made to learn the language and the path of least resistance often wins. So with puppies, it’s up to the humans to intentionally teach, because we can’t put that kind of responsibility on a baby.” As the owners and caretakers of these puppies, it is up to us to help them avoid developing unhealthy relationships with other puppies.

What we call “Littermate Syndrome” can vary from case to case. In some cases both dogs may become incredibly stressed when separated and either shut down or frantically try to find their partner. In some cases, one may be fairly confident without the other, while the second dog is terrified without the more confident dog. Dogs with “Littermate Syndrome” will often choose their partner over interacting with people or other dogs. In the majority of cases we can work on building each dog’s confidence and developing relationships outside of the bond with their partner.

There are, however, cases in which “Littermate Syndrome” can be scary. In these cases we will see two dogs that become stressed when separated, but when together will often fight over resources. In many cases this gets bloody and owners are left scrambling to come up with a solution. This aggression is usually the result of a lack of social skills and communication between the dogs. Both dogs lack the skills to appropriately use or interpret body language signs that tell the other how they feel about certain situations. This makes it difficult to communicate when one is uncomfortable with the other approaching whatever the first dog has, whether that’s a toy, food, or just their personal space. Without the ability to tell one another how they feel about things, they quickly learn that the only way to create any space is to physically force the other dog to move away through fighting.  In these situations, it is often recommended the dogs be separated (usually by re-homing one) and work on each dog’s training individually.

“Littermate Syndrome” does not only occur in puppies related to one another, but can occur in any set of puppies of a similar age that are not taught how to be independent of one another. The key to avoiding “Littermate Syndrome” is treating the dogs like they’re individuals, developing a relationship with each of them, and having them experience the world independently of one another. That doesn’t mean they can never spend time together, but there needs to be plenty of opportunities for them to grow and learn apart from the other puppy.  Bringing two puppies home means twice the work.

Signs of “Littermate Syndrome”

How to Avoid “Littermate Syndrome”

Avoiding “Littermate Syndrome” is possible, but it takes a lot of work. If you don’t think you’re reasonably capable of putting in that kind of work, don’t get two puppies at one time. If you feel like your dogs might have developed a codependent relationship, reach out to a trainer.