If you’ve been researching about bringing home a new puppy, you may have come across the term littermate syndrome. Littermate syndrome describes the relationship between littermates, often referring to sibling attachment or rivalry. Here’s what you need to know about littermate syndrome in dogs:

What is Littermate Syndrome in Dogs?

Littermate syndrome, or littermate dependency, is a non-scientific term for the relationship between siblings in the same litter. Usually, this refers to less-than-desirable behavior between the siblings and might be aggression or intense attachment. It typically refers to two or more siblings raised together and adopted into the same home.

There are a few things that can occur. Some dogs may develop aggression towards one another as they grow up. Or, they may become so intensely attached to one another that they experience anxiety or fear if they’re separated, even for a short period of time.

Even though there isn’t scientific proof of this phenomenon, many believe siblings should not be adopted into homes. However, even the anecdotal evidence doesn’t suggest this is a common occurrence and dog experts like behaviorists, veterinarians, etc. do not recognize this as a syndrome, and instead may use it as a label to describe a specific set of behaviors within a sibling context. After all, behavioral issues like aggression and intense attachment can arise in two dogs that aren’t littermates.

What Age Does Littermate Syndrome Start in Dogs?

Signs of littermate syndrome often develop in puppies at the age of eight to ten weeks. Of course, this may depend on when the puppies are brought to their new home.

Most puppies are often taken to their new homes at around eight weeks, so signs of littermate syndrome may begin to show. If you adopt sibling dogs that are slightly older, even close to a year old, those signs may show as they age into adolescence.

3 Signs of Littermate Syndrome in Dogs

Here are a few signs of littermate syndrome to look out for:

1. Resource Guarding

Dogs can become territorial over toys, shared water bowls, food, and sleeping areas. When one dog guards resources like food and water, the other dog may become scared to eat or drink. This territorial behavior is called resource guarding and is a common cause of aggression in dogs.

2. Aggression

There are many causes of aggression in dogs. With littermate syndrome behaviors, sometimes two sibling dogs raised together can develop aggression towards one another. Or, one dog may develop aggression while the other does not. This behavior can include snapping or growling at the other dog when they are near each other. The dog may seem uncomfortable in the presence of their sibling and may act out.

However, sometimes play-fighting can be mistaken for aggression. From a human perspective, the way dogs play can seem like a fight, too rough, or a precursor to aggression. It’s important to monitor your dog’s body language to determine if dogs are fighting or just playing.

3. Anxiety

In some cases, dog siblings might develop intense attachment to each other. This might mean the two dogs have separation anxiety, even for a very short time. They also may exhibit fearful behavior of new people, dogs, and situations. One or both siblings may present with this behavior.

It’s important to note that these signs of littermate syndrome are not scientifically backed. These behaviors can arise in dogs that are not caused by littermate syndrome. If you do have littermates and these signs show up, you should assess each dog individually. Don’t just assume it’s littermate syndrome. This prevents your dogs from getting the right behavior training and help they need to become independent dogs that get along well.

How Common is Littermate Syndrome in Dogs?

Because littermate syndrome isn’t actually recognized as a syndrome, but rather a description of specific behaviors among siblings, there’s not enough research to show how common or uncommon this phenomenon is. Even the anecdotal evidence suggests that it’s uncommon.

Can Littermate Syndrome Be Cured?

If you believe your two dogs exhibit littermate syndrome traits, intervening early is important. You will need behavior training that is done separately with each dog. This will teach both dogs to be independent of one another.

How to Prevent Littermate Syndrome in Dogs

There is some behavior training that can be done to help prevent littermate syndrome in dogs. As mentioned earlier, early intervention and socialization are key. This may mean starting to implement certain tactics even before your dogs begin exhibiting signs of littermate syndrome. There are a few important things to try to help your dogs become properly socialized:

1. Obedience Train Separately

Obedience training doesn’t only include training your dog how to be a good dog citizen. It also builds confidence and helps them learn how to interact with dogs and humans. It also helps your dog build a strong bond with you and separate them from their siblings.

There are many benefits of puppy training classes. If you’re enrolling both dogs in training classes, consider enrolling them in different classes. It may seem like a hassle, but it will be worth it in the long run when they both have individual personalities and are confident on their own without the other one present.

2. Crate Siblings Separately

Separating young siblings may seem cruel at first but ultimately, it will help your dogs gain confidence on their own. Crate training your dogs is important because each dog will have space to feel safe.

You can start by keeping their crates right next to each other to help ease anxiety, but after a week or two, start putting some distance between the two crates. Eventually, move the crates to entirely different parts of the home. This will help both dogs feel independent while still giving them opportunities to interact with each other as they wish when outside of their crates and in shared spaces of the home.

3. Spend Individual Time With Each Dog

Plan fun outings for each dog separately. The goal in preventing littermate syndrome is to help each dog gain confidence on their own and to rely on their owner, not their sibling.

Going on outings to the dog park, a dog-friendly restaurant, or even on a regular walk helps each dog become socialized in their environment. This also helps you to build a bond with your dogs, which helps prevent littermate syndrome.

4. Bring Them Together for Some Activities

Once both dogs seem confident and independent from one another, it’s time to branch out into some joint activities. During these joint activities, be sure to be on the lookout for potential signs of anxiety. If you notice any of these, take note, help your dogs’ anxiety, and create a plan to address these behaviors.

Try taking both dogs on a walk but with each dog walked by a different person. Walk together for five or ten minutes and then separate the two dogs. If you see any signs of anxiety in either dog, more separate training may be necessary.

Also, try behavior and obedience training together. For some of the training, work on training your two dogs together. For the other half, train each dog separately but in the same space. Also, work on moving the dogs in and out of sight from one another. This can normalize their sibling sometimes being around and other times being in a separate area.

It’s important that you continue to do behavior and obedience training with each dog individually. This continues to build confidence and independence in your dogs which can lead to healthier sibling relationships.

This is just an overview of what you need to know about littermate syndrome in dogs. It can be hard to raise two puppies at once so it’s important to be aware of this phenomenon. With proper training and socialization, you can help your dogs adjust to living together in a healthy way.