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 the report.
Children should be taught at school how to be good owners in the face of research showing "fundamental" gaps in knowledge about animal welfare, the PDSA said.
More top news
Government minister Justine Greening has apparently opened up about her sexuality, as thousands took part in the London Pride parade.
Record crowds are at this year's Pride in London parade as people show their support for the LGBT community after the Orlando shooting
After a showery start to the day, parts of Northern Ireland, western Scotland and south-west England will see drier conditions.