People who have new puppies, and those that work with them, often talk about the importance of socialization. Some of the research for the timing of the socialization period was done quite a while ago, and we also have more recent studies on some of the consequences and benefits of socialization. Let’s dig into the science on canine socialization.

Socialization Period

We have a bit of research on the socialization period in dogs, however it is limited. This is primarily because in order to study this effectively, there would need to be dogs who have absolutely no socialization. From the few studies available, we know that ethically that would be bad for their welfare, as they may struggle with fear and anxiety, and may be incapable of forming social bonds.

The socialization period is not incredibly well defined even though we talk about it frequently. One definition from Appleby (1993) is: a period of time where animals are more receptive to new stimuli and when social preferences are established.

The beginning of the socialization period is a bit easier to determine as it is tied to development.

The socialization period begins around 3 weeks and is associated with the following changes in physical development: 

  • Tooth eruption around 3-4 weeks of age, puppies can begin to eat solid food

  • Eyes are completely open by 3 weeks, allowing for visual stimuli

  • Ear canals fully open by 4 weeks, puppies will begin to give startle response to sound

  • EEGs show brain waves differentiate between sleep and wake states around 3 weeks of age

Some of the pioneering work into the critical period of socialization was done by Scott and Fuller and was published in the book ‘Genetics and the Social Behavior of the Dog’. They had groups of puppies in an outdoor enclosure with no human contact, and had some of the puppies removed at various ages to complete behavioural tests with people.

Dogs that had no experience with people and then were introduced at 7 weeks were most likely to quickly adapt; approaching people, taking treats from people, and walking on leash without extreme fear. Dogs taken from the outdoor enclosure after 7 weeks of age quickly declined in their ability to be socialized, and the authors concluded that the end of the period of socialization is in the neighbourhood of 12 to 14 weeks. 

Socialization period in dogs is from approximately 3 weeks of age to 12-14 weeks of age.

How do we socialize dogs?

When I discuss socialization with clients, or when teaching, I discuss exposures to:

  • People

  • Dogs 

  • Other animals

  • Sounds

  • Environments

  • Surfaces

  • Handling

We want dogs to have a variety of these experiences in a POSITIVE manner. In addition, considering the goals for the dog and the family that they are living with is important, so that those can be incorporated into the socialization plan for the puppy.

In my own research, ⅓ of the puppies in our sample had minimal exposure to people and dogs outside of the home (which was defined as exposure to 10 or less people and 5 or less dogs during a two week period) (Cutler et al., 2017).

Another study looked at adult dogs that had contact with children during their socialization period, defined as more than 2 – 20 minute periods per week. They tested dogs with a young child who called the dog by their name repeatedly, walked up to the dog, and then ran around in front of the dog. Dogs that had been in contact with children during their socialization period did not show any aggression or high arousal with the child, whereas dogs that had not been exposed to children during the socialization period did (Arai et al., 2011).

One other study looked at additional socialization to puppies under 6 weeks of age. This was intentional additional activities beyond some average socialization that was done with their puppies. Puppies received exposure to tactile, auditory and visual stimuli, as well as interactions with people and different environments. At eight months of age, the researchers found the puppies that experienced extra exposures had decreased separation related behaviour, were less distracted during interactions, had decreased general anxiety, and decreased body sensitivity (Vaterlaws-Whiteside & Hartman, 2018).

Behaviour problems and socialization

One of the main reasons we discuss puppy socialization is due to the potential influence on future behaviour problems. 

Associations between fear and poor socialization have been found in several studies.In one study, a socialization score was developed based on puppy exposure (between 7-16 weeks of age) to unfamiliar people, dogs, busy areas with people and transportation. Those with lower scores were more likely to show fear towards unfamiliar people and dogs as adults (Puurunen, 2020).

Another study looked at owner questionnaires completed for a large population of adult dogs. Those that had poorer socialization were more likely to be fearful as adults. Additionally, dogs that had noise sensitivity but no other anxiety problems, were less likely to be well socialized (Tiira & Lohi, 2015).

Poor socialization has also been associated with aggression in adult dogs. In a study that looked at aggression and avoidance towards unfamiliar people, researchers found an association with lack of experience to busy urban environments between 3 and 6 months of age, of which the socialization period overlaps. The assumption is that a dog would have had more exposure to people, dogs and other new experiences in an urban setting. (Appleby et al., 2002).

Puppy classes

Many dog owners mistake puppy classes for effective socialization. Puppy classes give the opportunity to provide socialization during classes themselves, but also to educate about socialization opportunities throughout the socialization period.

Some of the newer socialization research has involved puppy classes and their correlation or effect on future behaviour, training methods used, and retention in the home. Firstly, one study found higher retention in home if puppy classes were taken with dog (Duxbury et al., 2003). In the study they surveyed owners of dogs that were adopted from a humane society during their socialization period. At the time of the survey, dogs were between 1 and 6.5 years old, and those puppies that participated in the shelter socialization classes were more likely to still be in the home than those that did not.

One reason that puppy classes were not recommended in the past is the potential risk for disease transmission, especially parvovirus. A study looked at this specifically, and results indicated that vaccinated puppies (with at least one vaccine) attending socialization classes were at no greater risk of parvovirus infection than vaccinated puppies that did not attend those classes (Stepita et al., 2013).

One other study that tried to tease apart puppy class attendance at different ages, looking at groups of puppies that participated in classes between 1 and 3 months of age, at 4 months, or between 5 and 6 months of age. There was no significant difference in adult behaviour problems between those groups. However, when compared to dogs that had not done puppy classes during their first 6 months of life, the dogs that had some pre-adolescent training before 6 months of age had decreased odds of aggression, compulsive behaviours, destructive behaviours, and excessive barking as adults (Dinwoodie et al., 2021).

There are other studies that have looked at adult behaviour and whether or not puppies had attended classes or not, finding no significant difference between groups of dogs. There are so many differences between puppy training programs, methodologies, and techniques that it would take some huge epidemiological studies to tease out aspects that may or may not be beneficial. My own research found a huge range in puppy class programming, that a majority of puppy classes taught basic commands, and about 70% included puppy play time, but other socialization such as listening to noises was infrequent.

Other ways to socialize

An interesting study looked at the use of video in puppies 3-5 weeks of age, right at the beginning of the socialization period. They found that the puppies would watch the TV, and those exposed to it during that time period were less fearful of new objects at 8 weeks of age (Pluijmakers et al., 2010). This was only studied during that particular time point, so something to examine further, and a good possible option for additional socialization that can be done in the home.

AVSAB Position Statement 

The American Veterinary Society for Animal Behavior has a position statement available about puppy socialization and it’s an excellent resource for pet professionals and owners, and gives a brief overview of some of the science behind puppy socialization. The statement also addresses the parvovirus concern, and it’s their opinion that the risk of the behavioural consequences of poor socialization outweighs the small risk of disease transmission when done in a safe manner.

They state:

“The primary and most important time for puppy socialization is the first three months of life.During this time puppies should be exposed to as many new people, animals, stimuli and environments as can be achieved safely and without causing over- stimulation manifested as excessive fear, with- drawal or avoidance behavior. For this reason, the American Veterinary Society of Animal Behavior believes that it should be the standard of care for puppies to receive such socialization before they are fully vaccinated.”


The socialization period in dogs runs from approximately from 3 to 12-14 weeks of age. During this time, positive experiences to many different exposures are recommended. Research has shown associations between socialization and future behaviour problems.

Educating people with new puppies on the benefits and how to socialize their puppies could help to prevent some future fear and aggression.

Note – This post contains many references to research on puppy socialization, which are listed below. This is not an exhaustive list of all the research in this area.


Appleby, D. L., Bradshaw, J. W. S. & Casey, R. A. 2002. Relationship between aggressive and avoidance behaviour by dogs and their experience in the first six months of life. Veterinary Record. 150, 434–8.

Arai S, Ohtani N, Ohta M. 2011. Importance of bringing dogs in contact with children during their socialization period for better behavior. Journal of Veterinary Medical Science. 73:747–752.

American Veterinary Society of Animal Behavior. AVSAB position statement on puppy socialization. Available at:

Cutler, J.H., Coe, J.B., Niel, L. 2017. Puppy socialization practices of a sample of dog owners from across Canada and the United States. Journal of the American Veterinary Medical Association. 251:1415-1423.

Dinwoodie, I. R., Zottola & Dodman, N. H. 2021.An Investigation into the Impact of Pre-Adolescent Training on Canine Behavior. Animals. 11: 1298.

Duxbury M.M., Jackson J.A., Line S.W. 2003. Evaluation of association between retention in the home and attendance at puppy socialization classes. Journal of the American Veterinary Medical Association. 223:61–66.

Pluijmakers, J. J. T. M., Appleby, D. L., Bradshaw, J. W. S., Paulus, M. P. & Mol, J. A. 2010. Exposure to video images between 3 and 5 weeks of age decreases neophobia in domestic dogs. Applied Animal Behavior Science. 126, 51–58.

Puurunen, J., Hakanen, E., Salonen, M.K., Mikkola, S., Sulkama, S., Araujo, C. & Lohi, H. 2020. Inadequate socialisation, inactivity, and urban living environment are associated with social fearfulness in pet dogs. Scientific Reports. 10:3527.

Scott J.P., Fuller J.L. 1965. Genetics and the social behavior of the dog. Chicago: University of Chicago Press.

Stepita M.E., Bain M.J., Kass P.H. 2013. Frequency of CPV infection in vaccinated puppies that attended puppy socialization classes. Journal of the American Animal Hospital Association. 49:95–100.

Tiira, K. & H. Lohi. 2015. Early life experiences and exercise associate with canine anxieties. Plos One. 10:1-16.

Vaterlaws-Whiteside, H. & Amandine Hartmann, A. 2017. Improving puppy behavior using a new standardized socialization program. Applied Animal Behaviour Science. 197:55-61.