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Singleton Puppy Syndrome: One Puppy Litter

One doesn’t have to be the loneliest number when it comes to your dog.

by Karen B. London, PhD
June 10, 2021
single puppy standing outside
Sigma s / Adobe Stock

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Have you ever met a dog named Solo, Uno, or Only? It may not be just a cute name. The first question I consider asking is whether the dog was the only puppy in its litter. It’s rare, but dogs can give birth to just one pup — called a singleton puppy — and that can actually cause issues for the dog (and its human parents) down the road. 

What’s the Deal With One Puppy Litters?

For dogs, like many other species, early experiences are critical for normal social development. The time for true socialization — during which puppies will learn lessons that directly affect lifelong behavior — lasts from weeks 3 to 12. That's why it is pretty well known that puppies have the best chance for normal social development if they are allowed to be with their littermates for 7 to 8 weeks at least. This is why it’s not encouraged for puppies to be separated from their littermates or at least to have the opportunity to get to socialize with them for the first few weeks.

In a typical litter of three to twelve puppies, there is constant physical contact. The puppies crawl all over each other, and they are used to the warmth, the contact, the interruptions, and the movement that result from being in a pile of dogs. Unlike with Littermate Syndrome, the behavior problems of singletons are a result of them being alone with little feedback and correction.

Behavior Problems with Singletons

Littermates are a puppy’s first teachers, one of several reasons that it’s beneficial for puppies to stay with their litter for about two months. As the young dogs play, they use their mouths to tug or gnaw on their siblings’ ears, tails, paws and loose skin. If one puppy mouths another too hard, the puppy who got hurt will yelp, stop playing and move away. This teaches puppies that hard bites, even if not intended to cause pain, result in an interruption in play. Singleton puppies and those taken from their litter before the age of five or six weeks often lack proper bite inhibition. Puppies need their littermates’ feedback to learn to control the pressure they exert with their mouths.

The problems that singleton puppies are prone to having are the result of not being raised in this traditional litter environment. Along with lack of bite inhibition, typical problems in singletons include being unable to get out of trouble calmly and graciously, an inability to diffuse social tension, inability to handle frustration, lack of social cues and skills, lack of impulse control, and touch sensitivity.

Raising A Singleton Puppy

If you find out that your dog is a singleton puppy early — anytime before the puppy heads to your home — there are things that can be done. Be sure to work on teaching bite inhibition, and handle the puppy a lot to avoid issues with touch sensitivity. Any gentle, regular handling is likely to help. Have the puppy spend time with other puppies of the same age as much and as early as possible. 

If at all possible, you may even consider raising the singleton puppy with another litter. Getting to spend a lot of time with another litter lets a singleton puppy have a more typical or normal experience as a young puppy. The adorable play between puppies, which is so enjoyable to watch, is anything but light-hearted frivolous behavior — it provides puppies the foundation for normal, healthy social behavior as adults in many contexts and is a critical part of a puppy’s development and education.

One Singleton Puppy’s Story

A while ago, I met a two-year-old singleton Irish Water Spaniel. He was full of himself, had no frustration tolerance, little self control and almost no impulse control. His issues with frustration and control led to leash aggression with other dogs. His owner, who had actually bred him, was able to turn his behavior around, but it was a huge project.

The next litter from the same female was also a solo puppy who turned out fine and totally normal, except for being a bit large for the breed, which is not unusual for singleton puppies. The owner did everything right with her second singleton puppy: She raised her with a Lab litter that was only a few days different in age than the solo puppy, and did everything else I advised. She did end up spaying the breeding female after the second singleton as there was too high a risk of it happening again.

This second singleton puppy, benefiting from all the owner did to help her, was in no way behaviorally challenged like most singletons puppies are. The singleton turned out completely normal from a behavioral perspective, despite an unusual beginning, and this is an amazing accomplishment.

So, if you find yourself with a singleton pup, work on teaching bite inhibition early on, handle the puppy often to discourage touch sensitivity, help the puppy experience interruptions and frustration, and most importantly encourage the puppy to spend time with other puppies of the same age as much and as early as possible in those first 12 weeks.

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karen london

Karen B. London, PhD

Karen B. London, Ph.D., is a Certified Applied Animal Behaviorist and Certified Professional Dog Trainer who specializes in working with dogs with serious behavioral issues, including aggression, and has also trained other animals including cats, birds, snakes, and insects. She writes the animal column for the Arizona Daily Sun and is an Adjunct Professor in the Department of Biological Sciences at Northern Arizona University. She is the author of six books about training and behavior, including her most recent, Treat Everyone Like a Dog: How a Dog Trainer’s World View Can Improve Your Life.