Owners who fail to socialise and obedience-train dogs at an early stage are fuelling "frightening" levels of problem behaviour in their pets, according to a report by a veterinary charity.
Children should be taught at school how to be good owners in the face of research showing "fundamental" gaps in knowledge about animal welfare, said the PDSA.
The charity said 1.3 million dogs across the UK were displaying "problem behaviour" with nearly one in three, or 30%, of dog owners reporting being bitten or attacked by a dog.
More than half of dog owners, or 51%, said they knew someone who had been bitten or attacked by a dog while a separate survey of children found nearly two thirds, or 65%, reported having been frightened or scared by a dog's behaviour.
In some cases dogs have been deliberately trained to be aggressive but the primary cause of anti-social behaviour in dogs was a lack of socialisation and basic obedience training when dogs are young, said the report.
The majority of dogs, at 61%, had not attended training classes within their first six months of life, according to the findings.
The research forms part of the second PDSA animal wellbeing report which claims obesity, aggression and illness are set to take over the pet population if they are not tackled.
An estimated 18.5 million dogs, cats and rabbits are being fed unsuitable diets and treats in spite of their owners knowing about the health risks, said the report.
The charity warned that an estimated 11.2 million pets are not vaccinated or neutered, leaving them at "serious" risk of developing potentially fatal illnesses.
PDSA senior veterinary surgeon Sean Wensley said: "Each year there are awful stories of dogs attacking pets and people, sometimes with fatal consequences. Tackling this begins with owners and breeders taking full responsibility for their dogs' behaviour and adequately socialising and training them from a young age."