Dogzen general manager Kim Morrisey said the first one to four months was critical.
"Dogs need to be socialised broadly in that period and people make the mistake at vaccination time to keep their dogs locked away."
But what needed to happen, Morrisey said, was that pets need to be introduced to different people, cats, dogs and other animals and different situations.
"This is getting them used to novelty and change of different noises and different experiences."
It could be scary for dogs as they got older so those formative years were crucial to broaden their socialisation.
Morrisey said although dogs create the same hormonal response in us to treat them like humans, "they are not human, they need to be related to in dog terms".
"Love them with all your heart but treat them with what they need."
Adult dogs with behavioural problems are "taken back to the den, into a learning state".
"We are rewiring the brain and getting rid of old behaviours."
But it's not only the dogs that need to change behaviours.
"This is a shared language and humans need to be retrained."
DNA analysis published in 1997 suggests all modern dogs are descendants of the gray wolf, domesticated about 130,000 years.
This means that wolves began to adapt to human society long before humans settled down and began practising agriculture.
This domestication may have happened twice, producing groups of dogs descended from two unique common ancestors.
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