Should Dog Owners Be Worried About Littermate Syndrome?
If you’re wondering “should I get a second dog“, you’ve probably come across the term ‘littermate syndrome’ on the internet. According to some, littermate syndrome can make your dogs aggressive, anti-social, anxious, and untrainable, while others say that this phenomenon is purely the result of irresponsible dog ownership.
So, does littermate syndrome exist, or is it a myth? Should you be concerned about getting two puppies at once, or will your pups be instant and forever best friends for you and your family? Let’s get into it.
What Is Littermate Syndrome?
Littermate syndrome is a term given to a particular phenomenon observed in certain pairs of puppies raised together. Most commonly seen in puppies from the same litter (and thus dubbed littermate syndrome,) in some cases puppies from different litters that are around the same age can also show signs of this behavior. Puppies with littermate syndrome become extremely attached to their “littermate,” whining, becoming destructive, and struggling to socialize when not with their preferred dog friend.
There are no official studies confirming that littermate syndrome is a verifiable condition, but many breeders, veterinarians, and dog owners have observed puppies exhibiting these behaviors.
“If you’ve ever watched a litter of puppies at play, you’ve probably wondered: Do dogs know their siblings? From the beginning, pups recognize their littermates primarily by scent and that recognition is strongest when they are young.” 
– Dr. Karyn Collier, medical director for wellness medicine at Saint Francis Veterinary Center of South Jersey
While it’s not a guarantee that two puppies from the same litter will develop littermate syndrome, it’s generally inadvisable to buy two puppies at once. Breeders, behavioral experts, and vets usually recommend that dog owners get one puppy at once and wait until they are at least one or two years old before introducing a new puppy to the family.
Can All Breeds Get Littermate Syndrome?
Yes! Littermate syndrome is not breed-specific, and puppies of any kind can develop littermate syndrome if raised with their sibling. In some cases, young puppies from different litters raised together can also bond to the point of developing littermate syndrome.
Littermate Syndrome Symptoms
Because littermate syndrome is not a medical disorder, it does not have true symptoms. However, there are some signs you can look for to determine whether your puppies are developing a bond that could cause them to struggle to function separately.
- Whining, destructive behavior, excessive barking, ignoring basic commands when separated from each other.
- Anxiety in new situations and with new people or dogs.
- Unwillingness to eat, play, walk, or follow commands alone.
- Training delays.
In some cases, littermate syndrome can escalate to littermate aggression, wherein the two dogs fight with one another in high-stress or unfamiliar situations. Dogs feed off of each other’s energy, and when dogs are more closely bonded, they will be even more sensitive to each other’s moods. When littermate syndrome dogs become anxious, it can sometimes escalate.
Is It a Myth? The Littermate Syndrome Controversy
Littermate syndrome exists, but it is also not an official diagnosis. There is very little evidence to suggest that littermate syndrome is anything more than a strong emotional bond and reliance, which isn’t uncommon for young humans and other animals raised together.
While littermate syndrome absolutely can be detrimental to a puppy’s development as a confident and independent dog, there isn’t anything wrong with them for bonding closely with their sibling.
Littermate syndrome has become controversial both because it is over-exaggerated, and because it is underplayed, while the truth lies somewhere in the middle.
Littermate Syndrome FAQ
Wondering whether your puppies could have littermate syndrome? Here are some of the most common answers other dog owners have about this phenomenon.
What Are Signs Of Littermate Syndrome?
In most cases, littermate syndrome manifests as an extreme dependence on the other dog. Dogs with littermate syndrome will often show signs like:
- When separated from each other, dogs whine, perform destructive behavior, bark excessively, and ignore basic commands.
- Anxiety when confronted with new situations or people.
- A refusal or inability to eat, play, walk, or follow commands alone.
- Delays in training.
Does Littermate Syndrome Go Away or Can It Be Cured?
With preventive measures, you can prevent your puppies from ever developing littermate syndrome. If you find that your puppies have spent too much time together and have not had adequate time being trained and socialized alone, start doing so as soon as you can.
The sooner you start building your dog’s confidence in themselves, the less likely they will be to have long-lasting littermate syndrome. When left unattended, some dogs can become withdrawn, anxious to the point of aggression, and unable to enjoy regular life without their companion.
How Common Is Littermate Syndrome?
There is no official data to tell us just how common or prevalent littermate syndrome is, but enough vets and breeders have experienced this phenomenon that they often tell dog owners not to purchase two puppies at once.
Why Does Littermate Syndrome Happen?
Littermate syndrome happens when puppies spend too much time together and are not adequately socialized independently. These puppies bond very closely and become reliant on one another to perform everyday tasks. To prevent this, it’s important to train, feed, crate, and exercise your puppies separately.
Is It Bad To Have Two Puppies From The Same Litter?
No, it’s not bad, but you can run the risk of your dogs becoming more closely bonded with each other than they are with you. As mentioned, you can avoid this with purposeful independent training, exercise, and socialization with each puppy.
Is there Littermate Syndrome in Cats?
Yes! Two kittens from the same litter can develop extremely close bonds, and experience social disorders as a result.
What Age Does Littermate Syndrome Start?
Puppies are ready to separate from their moms and their littermates at around 8-12 weeks old. If kept together after this, littermates can begin to develop a much deeper, more codependent bond.
How To Prevent Littermate Syndrome?
If you have two puppies from the same litter, the best way to prevent littermate syndrome is to exercise, feed, play with, walk, and socialize the puppies separately as much as possible. Avoid crating them together at night, and make sure each pup receives plenty of love away from their sibling.
Do you ever wish your dog would get tired of barking? Chances are, they won’t.