Littermate Syndrome in Dogs - Is It Possible?

Littermate Syndrome in Dogs - Is It Possible?

Author WDF Staff | Last updated: May 03 2023


Getting a new puppy is one of the best feelings in the world, but getting two puppies should be better, right? They will have constant company and never feel alone, and what is wrong with that? As it turns out - quite a bit.

Littermate syndrome is not a widely-known term, and it can affect puppies adopted from the same litter. Owners often think that adopting brothers and sisters is a good thing. Still, if you don’t know what you are doing, sibling adoption can have pretty bad results. The problem with littermate syndrome is a lack of awareness and scientific studies. Most owners find out about it after researching why their puppies misbehave.

What is littermate syndrome?

There is no official definition, but many dog behaviorists, vets, and breeders define littermate syndrome as:

“Littermate syndrome in dogs occurs when two puppies from the same litter living together develop such a strong attachment to each other that it interferes with their ability to interact in a normal manner with other people, other dogs, or any situation where they are not together.”

According to Dr. Karyn Collier, a medical director at Saint Francis Veterinary Center of South Jersey, littermates that grow up together get so co-dependent that they cannot learn social rules and behaviors with other dogs humans. They often ignore their human family and focus only on each other.

dogue de bordeaux playing

How to spot littermate syndrome?

Keep in mind that the littermate syndrome might be hard to spot at first. Most owners credit misbehaving because puppies are still young and they are developing. There are three main issues involving littermates, and they are;

1. Hyperattachment

Littermate puppies that are growing up together often become hyper-attached. They are unable to cope with their environment without their littermate present. They can have a wide range of problems when they split, like panicked, fearful, and often aggressive behavior toward humans. Also, one puppy is usually dominant, and the other is submissive, which means one puppy is bullying the other. Hyperattached puppies typically don’t reach their full development potential.

2. Lack of socialization

Having two young puppies at home can be pretty hectic. Experienced owners usually know how to handle that, but new, inexperienced owners convinced by breeders to take two dogs can find themselves in quite a bit of a problem. Owners struggle to find their footing and are trying to survive the “madness” that comes with having two puppies.

Such a hectic situation means that the puppies don’t get enough training or socialization. Lack of these two things results in dogs with behavioral issues. Each puppy should receive their own training, potty training, socialization, leash training, and intro to obedience training. Organizing these things could be problematic, even for the most experienced owners. 

Puppies with littermate syndrome are 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.
According to Patricia McConnell, a certified vet behaviorist

She has personally seen dangerous levels of aggression amongst puppies from the same litter who stayed together after 10 weeks old.

litter puppies

3. Aggression

One of the biggest littermate syndrome problems is dog aggression. Siblings will probably start playing roughly. As they grow up, that rough playing can turn to aggression toward their siblings. Usually, there is a dominating puppy, and they develop into a real bully.

Dog owners often presume that socializing between siblings is enough, but that is a huge mistake. Littermate puppies need to socialize with other dogs and learn that their behavior might be appropriate at home, but other dogs might not tolerate it. They can quickly get scared of new situations and unfamiliar environments, which will most likely end up with aggression.

What to do about it?

If you have already adopted littermates - don’t panic! According to Dr. Melissa Bain of UC Davis Veterinary School, there are littermate puppies that can peacefully coexist and develop normally. She prefers not using the term “syndrome” because she believes it gives littermates a bad connotation.

It makes you think all littermates have problems, which is not the case.

Suppose you already have two puppies from the same litter at home, and you noticed their problematic behavior. In that case, there are some things you could do to ensure their healthy development. Here are some tips on how to handle the dreaded littermate syndrome;

puppies sleeping

1. Separation

Make sure each puppy spends time apart from their siblings daily. It is vital you work with them separately and train them, socialize, and play with them individually. Puppies will probably experience separation anxiety. Here is an interesting article that can help you deal with that problem - Separation Anxiety In Dogs - How To Stop It.

2. Crate training

Keeping your puppies inside their crates will make handling them more manageable. Plus, it is also for their safety a well. If you think they should share a crate, you would be mistaken. It is a more affordable option, but the professional advice is to separate their crates and place them in different parts of your house/apartment. Check out this helpful guide on how to successfully crate train your dog - Crate training made easy.

3. Feeding

Make sure each puppy feeds independently. When it comes to littermate syndrome, puppies will often decline to eat alone. Make sure they get used to having their meals separately and from different bowls. You can learn more about the best puppy food here - Best puppy food.

4. Individual treatment

The two puppies can be similar, but they can also be very different. They can have different temperaments, energy levels, motivators, and preferences. One can be highly sociable, while the other can prefer being alone. Remember to treat them as the individuals they are.

puppies looking

5. Creating individual bonds

You must take your time alone with each puppy. They need to learn to focus on their owner and not strictly on each other. Your puppies should learn to obey your commands and behave even when their littermate is absent.

6. Socialization

You must start the socialization process as soon as the puppies receive their shots. Take them to different places together and separately. Make sure they learn proper behavior when they are on their own. Take each puppy individually to parks and walks and to meet new people and other dogs. Here are some ideas for proper socialization - Socialization Tips and Tricks.

Caring for puppies from the same litter can and will take time, but everything can be done with proper technique and knowledge.

World Dog Finder team

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