A licensed dog kennels in Co Tyrone has the worst conditions in the UK, it has been claimed.
Scenes inside Furnish Kennels in Fivemiletown showing dozens of young puppies without their mothers huddled together in disused trailers were shown as part of a BBC investigation programme last night.
The dog breeding industry in Northern Ireland is worth an estimated £160m.
As well as investigating dog breeders in Scotland, the programme travelled to Northern Ireland where it visited Furnish Kennels.
Run by brothers David and Jonathan Hamilton, it claims to be the largest licensed dog breeding establishment in the UK.
During filming at the kennels, the BBC said it found hundreds of breeding bitches in battery-farmed conditions, as well as dozens of pups, just weeks old without their mothers, huddled together in disused trailers outside the main building in freezing conditions.
In a statement through his solicitor, David Hamilton said his premises "are maintained and run in accordance with all relevant legislation and regulations in an entirely open and transparent manner. All dogs are under the supervision of a nominated veterinary surgeon".
The kennels fall under the responsibility of the local authority - now Fermanagh and Omagh Council.
The previous Fermanagh Council said the kennels were now called the UK Dog Breeding Academy, and were inspected four weeks ago and that no puppies were found to be kept in trailers on site. It said the premises complied with legislation. The footage of the kennels was blasted by Sheila Voas, chief veterinary surgeon with the Scottish government.
"It was barbaric. It was a production line. It was using animals as a commodity," she said.
The investigation also discovered traders who hide behind fake identities online to profit from the illegal sale of puppies and revealed that one in three dogs bought in the UK are now believed to have been bred on a puppy farm.
It also revealed that Liz Baird from Ayrshire, a dealer in the puppy industry who has previously been prosecuted and banned, is trading again.
Michaela Harvey told the programme that Ms Baird sold her a Jack Russell-Pug cross-breed puppy for £395 in an Ayrshire car park. The puppy she called Bane fell ill three days later and died.
She said: "He was just lying and he wasn't moving at all. But he was still breathing... he let out a kind of scream. It was the worst sound I've ever heard in my life. He was sick everywhere and he just died."
The Dog Factory was shown on BBC One Northern Ireland last night, and is now available to view on iPlayer.
It is estimated that one in every three dogs bought in the UK have been bred on a puppy farm.
The Ulster Society for the Prevention of Cruelty to Animals (USPCA) said the number of puppy farms is rising.
Puppy farms range from backyard breeders to commercial operations which rake in thousands of pounds.