Littermate Syndrome - Background History & Treatment Options
Category_Dog Knowledge

Littermate Syndrome - Background History & Treatment Options

by Andrew Ehlert

Getting two dogs at the same time might seem like a great idea at first. As most people know, dogs are social creatures, and you may believe having a set from the same litter means they can play with each other instead of participating in typical destructive puppy behaviors. Nearly 1.6 million dogs are adopted every year in the US, so it only makes sense that some adoptions are siblings.

However, many shelters, breeders, and other professionals strongly recommend that you avoid getting two puppies due to littermate syndrome. What sounds like a great idea on paper can end up causing long-term problems for you and the dogs.

What is Littermate Syndrome?

The term “littermate syndrome” refers to the behavioral issues that often come out when two sibling puppies have been adopted and raised together. Littermate syndrome usually affects dogs over 8-10 weeks old, which is when most young puppies are ready to leave their mother and become adopted into a family.

When puppies become old enough to be adopted out, many breeders and shelters separate the litter into different homes. This is in part because a new puppy can be difficult, and many adopting families are only interested in bringing one new dog into the house. However, another reason these puppies may get separated is littermate syndrome.

When puppies move into their new homes, they have room to mature physically, learn how to interact with new people and other animals, grow in confidence, and adopt essential survival skills like grooming. Puppies that stay in the same household are more likely to develop co-dependent relationships with their siblings.

Not every set of sibling dogs is guaranteed to deal with littermate syndrome, but there’s not a clear indicator of which dogs are likely to have littermate syndrome or not. Dogs are always on a situation-by-situation basis, but some symptoms might indicate whether a pair of pups are dealing with these issues.

Early Signs and Symptoms of Littermate Syndrome

There are several early symptoms of littermate syndrome and some that may not be obvious at first. For a while, it may seem like a dog is simply acting out or in need of basic obedience training, which is not unusual for many puppies. When these experiences become excessive, you may want to look into treatment.

Constant Fear of New People, Dogs, and Other Stimuli

Puppies dealing with littermate syndrome may avoid new people, dogs, or toys and become nervous when facing a new space. They are likely to retreat to their littermate in these instances instead of their new owner. They may also display signs of high anxiety, such as whining, barking, pacing, panting, or destructive behaviors when they are separated from their littermate.

Unwillingness to Be Alone

That fear can manifest itself in being unwilling to be alone in general, including eating or playing with a new toy or, worse, only eating or playing with a toy with their partner. This may be cute at first, but there are some long-term consequences. For example, if a dog passes away before its littermate, it can be more devastating than usual for the bonded dog.

Training Issues

Puppies from the same litter may also take longer to train or be avoidant of training in general. This is because they get distracted by each other. However, training dogs is essential. Not only does it make them better behaved, but it also helps build their confidence and provides mental stimulation.

Higher Aggression Toward Each Other

The final and often most worrying sign of littermate syndrome can be the high aggression between the paired dogs. Dog siblings may play rougher with each other than they would other dogs. This can cause severe injuries, and if it gets to the point where they must be physically separated, there can be a danger to the owner.

Treating Littermate Syndrome

If you have already adopted littermates or know you’ll have them soon, just know it is possible to do without major difficulties. There are a couple of things you can do to help prevent littermate syndrome from coming up.

While littermate syndrome can be complicated, it is not untreatable as long as it’s dealt with swiftly and permanently. Much like training a dog, you have to be clear about the rules and stick to them no matter what.


First, make sure to put training above all and keep the dogs separate. Being alone will help each dog get better used to being alone and make training easier overall. Depending on your schedule, this may include investing in time with a professional to have two separate training classes.

Teach Them to Be Alone

The goal is to keep sibling pups from developing too much dependence on each other, which means two of everything.

Make sure that each dog has their own:

  • Crate
  • Food bowl
  • Toys
  • Playtime
  • Walks

Ideally, you should begin walking them separately as soon as possible. This will get them used to being alone and allow you to stay the leader to the dog. As the leader, your dogs will look to you for social cues and commands instead of looking to their littermate.

However, the puppies must have some time together. It can help alleviate their aggression if you engage with them to support them getting along. Games such as fetch or tug-of-war are popular for those trying to keep their dogs from getting aggressive with each other.

Socialize Them With Other Dogs

Some dog owners claim that having another dog can help alleviate littermate syndrome, especially an older dog that has been in the house for longer. However, if you don’t have a third dog already, try to take them on playdates with other dogs or to the dog park. This should be done separately at first to help them independently build their confidence.

Overcoming Littermate Syndrome

Puppies can be overwhelming at first, and the idea of dealing with two puppies, both separately and together, may seem like too much. Only you will be able to tell what your dog truly needs, but taking these steps will help alleviate littermate syndrome and give your dogs a better overall quality of life.

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