Why You Need to Socialize Your Puppy

The importance of socialization can’t be stressed enough. Here's how we know - and what it means for puppy owners.

Puppies - like this cute pup walking along a log - must be socialized, and here's the research that first told us this

By Zazie Todd, PhD

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These days, more and more people understand that puppies need to be socialized. But sometimes people wonder, how do we know this? It’s based on classic research in canine science.

What does science tell us about the need to socialize puppies?

Many papers contribute to our understanding of puppies. In 1950, J.P. Scott and Mary-‘Vesta Marston published a study of 17 litters, including the earliest age at which they opened their eyes for the first time, began to walk, and engaged in play. They hypothesized there were critical periods in canine development. 

In 1959, C.J. Pfaffenberger and J.P. Scott noticed that puppies being raised to be guide dogs were more likely to fail their training if they were kept in kennels for longer and missed some early socialization.

Then in 1961, Daniel Freedman, John King and Orville Elliott published research on puppies in Science. They said, 
“the net result suggests that the seventh week of age was the period in which the pups were most receptive to socialization, and that 2½ to 9-13 weeks of age approximates a critical period for socialization to human beings.”
They studied eight litters of puppies (five of Cocker Spaniels, three of Beagles). It was an isolation experiment in which each mother and her pups were kept in a fenced one-acre field without any contact with people. Food and water was supplied via openings in the fence.

Every week, certain pups were taken from each litter for 7 days of socialization. The socialization does not match what people do for puppies nowadays; in fact, during their week indoors, the pup was played with, fed and otherwise taken care of, during just three thirty minute sessions per day. 

Pups were taken from their litters for socialization at either 2, 3, 5, 7 or 9 weeks of age. At the end of the week, they were returned to their mum and litter-mates. 

Every day during the socialization there was a 10 minute test of how much time the puppy would spend near the experimenter. The 2-week old pups were too young to really do anything. But by 3 weeks, they were able to interact with the experimenter and “spent most of the 10 minute period pawing, mouthing and biting him and his garments.” At 5, 7 and 9 weeks old it is reported that the pups were initially wary but then warmed up (within one play session, two days and three days respectively).

Puppies - like this cute Shar Pei - must be socialized to be calm, friendly, adult dogs. Here's the classic research that showed this - and what it means for you.
Photos: Lex-art (top) & Zuzule (both Shutterstock.com)

At 14 weeks old, all of the puppies were removed from the field and tested over the following 2 weeks.

Five puppies acted as ‘controls’ and remained in the field with their mother the entire time. The result of not being socialized was terrible. 

The scientists said, 
“unless socialization occurred before 14 weeks of age, withdrawal reactions from humans became so intense that normal relationships could not thereafter be established.” 
One of the control puppies was “petted and fondled” every day for the following three months, and did not really become more sociable in that time. 

It’s interesting to look back at this article because science – and dog training – has improved since it was conducted. (For example, there is a greater trend towards using positive reinforcement in dog training). 

Full details of the socialization are not given and the numbers of puppies are small. These days proper desensitization and counter-conditioning would be used for a fearful pup as subjecting it to unwanted petting could make it even more fearful. (See how to pet cats and dogs to learn how to give puppies a choice to be petted or not; and if you have a fearful dog, see eight tips to help fearful dogs feel safe). 

Nonetheless, these results tell us a lot. They tie in with other studies of the time, including raising Chihuahua puppies with cats (Fox, 1969). They relate to what is known about sensitive periods inother animals (including humans). But now that we know how harmful lack of socialization is, the study would not be repeated today.

Research into the socialization of puppies is ongoing. Recently, scientists discovered that in some breeds, the sensitive period for socialization may end sooner (Morrow et al 2015). This means that socialization must begin at the breeder, before you even bring your puppy home, which is one reason to take great care when you choose a puppy

In fact, research on an early socialization program for Guide Dog puppies aged 0-6 weeks found that it brings big benefits in terms of later behaviour (Vaterlaws-Whiteside and Hartmann, 2017). As well, we also know that many puppies are missing out on important socialization opportunities.

What does socialization of puppies mean?

Socializing puppies is about more than just people. It involves pleasant experiences with unknown dogs, surfaces, places, anything that puppy might come across as an adult. Socialization should start in the home of the breeder, or the foster home if it is a rescue (puppies are available from rescues too). If you’re getting a puppy, ask the breeder or rescue what they do to socialize puppies, and be prepared to do lots of socialization yourself.

In her book Culture Clash Jean Donaldson says,
“it’s advisable to go way overboard covering all the bases before the socialization window closes, especially for spookier breeds or individuals. This means exposing the puppy to as wide a social sphere as possible in terms of human age groups, sexes, sizes, shapes, colours and gaits. The experiences should be positive (play, treats, nothing scary) and include a wide variety of patting, handling and movement by the humans. 
"It also means getting the puppy used to anything it may have to encounter in later life, such as car rides, veterinary exams (make the first one or two fun rather than scary), cats, traffic, soccer games, elevators and pointy sticks.”
There is a balance to be struck in socializing puppies to prevent future behaviour problems and protecting them from disease when they are not fully immunized. This is something to discuss with your vet. The AVSAB position statement on puppy socialization says, 
“Because the first three months are the period when sociability outweighs fear, this is the primary window of opportunity for puppies to adapt to new people, animals and experiences. Incomplete or improper socialization during this important time can increase the risk of behavioural problems later in life including fear, avoidance, and/or aggression. Behavioural problems are the greatest threat to the owner-dog bond… Behavioural issues, not infectious diseases, are the number one cause of death for dogs under three years of age.”
“The importance of a critical period for socialization is hard to overestimate,” says Jean Donaldson. It’s important to get it right. And because dog training is an unlicensed profession, this means you should choose your puppy’s dog trainer with care.

If you liked this post, check out my book Wag: The Science of Making Your Dog Happy. Modern Dog magazine calls it "The must-have guide to improving your dog's life."

What are your tips for socializing a puppy?

You may also like:
Top tips on puppy raising from the experts (Guide)
Make your dog happy: How to choose a puppy class
How to choose the right puppy in 4 easy steps: A guide

Zazie Todd, PhD, is the award-winning author of Wag: The Science of Making Your Dog Happy and Purr: The Science of Making Your Cat Happy. She is the creator of the popular blog, Companion Animal Psychology, and also has a column at Psychology Today. Todd lives in Maple Ridge, BC, with her husband, one dog, and two cats. 

Useful links:

Donaldson, Jean (2005, 2nd edition). Culture Clash: A revolutionary new way of understanding the relationship between humans and domestic dogs. Dogwise.
Fox, M. (1969). Behavioral Effects of Rearing Dogs With Cats During the 'Critical Period of Socialization' Behaviour, 35 (3), 273-280 DOI: 10.1163/156853969X00242  
Freedman, D., King, J., & Elliot, O. (1961). Critical Period in the Social Development of Dogs Science, 133 (3457), 1016-1017 DOI: 10.1126/science.133.3457.1016
Morrow, M., Ottobre, J., Ottobre, A., Neville, P., St-Pierre, N., Dreschel, N., & Pate, J. (2015). Breed-dependent differences in the onset of fear-related avoidance behavior in puppies Journal of Veterinary Behavior: Clinical Applications and Research, 10 (4), 286-294 DOI: 10.1016/j.jveb.2015.03.002
Pfaffenberger, C., & Scott, J. (1959). The Relationship between Delayed Socialization and Trainability in Guide Dogs The Journal of Genetic Psychology, 95 (1), 145-155 DOI: 10.1080/00221325.1959.10534251  
Scott, J., & Marston, M. (1950). Critical Periods Affecting the Development of Normal and Mal-Adjustive Social Behavior of Puppies The Pedagogical Seminary and Journal of Genetic Psychology, 77 (1), 25-60 DOI: 10.1080/08856559.1950.10533536
Vaterlaws-Whiteside, H., & Hartmann, A. (2017). Improving puppy behavior using a new standardized socialization program. Applied Animal Behaviour Science, 197, 55-61. https://doi.org/10.1016/j.applanim.2017.08.003

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