And what is Socialisation anyway??
I pick up the phone to take an enquiry from someone wanting to book private puppy training. The client says “My puppy is well socialised but I want one to one training”. So I ask “oh, how old is your puppy?” the client replies “9 weeks old. But he was reared with three other adult dogs, his litter mates and the breeder had grandchildren. He also lives with another dog”.
Is this puppy well socialised? What does socialisation mean anyway?
When your puppy is born the first 2.5 weeks are devoted to suckling and keeping warm. By 2.5 weeks old most puppies are beginning to open their eyes and ears. At this stage, rapid brain development takes place until roughly 10-12 weeks old. 
The brain development at this age is said to only develop at this stage and will only occur if the pup experiences a wide variety of stimuli (Fox, 1978). So experience shapes brain development. After 10 weeks the brain development slows down significantly. Friedman, King and Elliot (1961), found that if a pup was starved of social experiences until 12 weeks, the pup became fearful and could never recover from that even with extensive socialisation efforts afterwards.
If, during the first 12 weeks, a puppy is exposed to people and dogs and feels fearful, the brain would be wired equipping the puppy with the means to perceive threat and make escape; the pup could become vigilant for danger. If the puppy has pleasant experiences with people and dogs during this 10 weeks, the brain will be wired to indicate people and dogs are safe and the pup will continue to be comfortable with dogs and people. So the emphasis on socialisation is that experiences should be nice so that the puppy can register them as safe. It is likely that it is more important that a puppy has positive and safe experiences at this stage than it is for them to have a high quantity of experiences if these are not all experienced as safe. Some dog experts (Dr Ian Dunbar) say that dogs need to have met 100 people before the age of 12 weeks, perhaps the same could apply to dogs since they also come in many different shapes, sizes and personalities. However, I suspect based on my experience, that some puppies with sensitive temperaments may not cope with so many as this could be considered flooding with such high numbers over such a short space of time and could risk sensitising (making more fearful) a timid puppy rather than habituating it. I feel more research is needed.
Equally, the puppy needs to experience a wide variety of stimuli in a wide variety of contexts. But the puppy must feel safe whilst having these experiences for them to be of value. Dogs are known not to generalise their learning very well and need to experience social exposure in a wide variety of contexts.
We know that at the onset of puberty (approx. 6-9 months of age) dogs experience at least one other sensitive period (Fox, 1971, Mech, 1970, Ryan, 2013). We also know that even if a dog has a variety of early social experiences, these can wear off if the dog then goes through a period of no social exposure, such as that experienced if a dog sustains an injury and has to have crate rest for several weeks or months. 
Loss of social exposure during the first year or so of a dog’s life can be very damaging and it might be that at certain stages of a dog’s life synaptic pruning takes place which could remove synapses that are not consistently being used at that time, these could be considered as non-essential and be pruned back to make way for “more important things” which might be more widely used. This means that if socialisation is not maintained, it can be pruned back which would render early socialisation useless.
Let’s go back to that phone call now. Is the puppy well socialised at 8 weeks after having met three adult dogs, grandchildren at the breeder and lives with another dog? Would it surprise you to know that many of the dog aggressive dogs I work with live with another dog? Socialising with one dog is simply insufficient. We also need to be assured of the quality of the social exposure with children. I saw a litter that had been mauled by the 18 month old grandchild and the pups were frightened of being handled. This could lead to issues later with children.
We know, with all the above information that the brain has some degree of plasticity, but this becomes less so after 10 weeks old. That is not to say that you cannot socialise a dog after this time because you can. However, the longer the delay is the more likely that the dog will lack some degree of adaptability. Techniques have also changed over the years and my experience tells me it is possible to form social learning later as long as you are very sensitive with how the dog is exposed. There are also individual differences between puppies so some are more adaptable than others, even against the odds. There are also breed differences relating to how early socialisation should be (Kopechek, 2010).
However, it is better to be safe than sorry. Early gentle social exposure is important. The puppy must feel safe when being exposed so that it can form safety history for future reference. Socialisation must be maintained well into adulthood. 
Negative social experiences are to be avoided, and if encountered, we should aim to produce even more positive exposure for that puppy as soon as possible to undo any damage caused.
The response to this phone call was that I could provide private training as long as I knew the puppy was attending well run puppy socialisation classes but that I felt classes would offer the client everything she needed as well as important social exposure.
We have a responsibility as trainers to ensure we offer the right service to our clients in the interest of their dog.
References
Freedman DG, King JA, Elliot O. 1961. Critical periods in the social development of the dog. Science, 133, 1016-1017
Ryan, D (2013) Dogs that Fight and Bite
Fox, M.W. (1978) The Dog: Its Domestication and Behavior. New York: Garland STPM Press.
Fox, M.W. (1971) Behaviour of Wolves, Dogs and Related Canids. New York: Harper and Row.
Mech, L. D. (1970) The Wolf: Ecology and Behaviour of an Endangered Species. New York: Natural History Press
Kopechek, M.K (2010) Variation in the Onset of Hazard Avoidance Behaviour in Three Breeds of Domestic Dog. Master of Science, Ohio State University, Animal Sciences.
