Puppies pictured in an oversized egg box to highlight puppy farming, which the Dogs Trust has dubbed 'battery farming' of dogs
Animal lovers are being duped into buying "farmed" dogs, a charity has warned.
As many as 900,000 people may have bought a dog from a puppy farm without knowing it, Dogs Trust claims.
In a recent survey of almost 900 pet owners carried out by the dog welfare charity, 95% said they would not buy a dog from a puppy farm.
But when asked where they had got their dog from, 15.1% said they had got it from a newspaper advert, the internet, a pet shop or a pet superstore - all of which are often supplied by puppy farms, the charity said.
It branded the trade "battery farming of dogs" and called for a review of dog breeding licensing legislation.
The charity said breeding bitches at battery farms are kept in small pens without natural daylight or contact with other dogs.
The dogs have little contact with people and no space to exercise or opportunity to play. They are bred continuously in these conditions until they are too old, and then discarded, the charity added.
Clarissa Baldwin, chief executive of Dogs Trust, said: "Battery farming of dogs is an appalling practice, abhorrent to all decent members of society.
"While most people would never consider buying a dog from such a place, it seems that a large number are inadvertently doing so."
Anyone thinking of buying a puppy should always find out about its background first, said the charity.