Illegal dog breeders are being warned they could face a fine of £200,000.
It comes after a dog breeder in Llandeilo was caught selling sick puppies with false pedigree and veterinary papers.
Dylan Huw Thomas, 59, was handed a 12 month suspended sentence and ordered to pay £215,000.
Philip Hughes, Carmarthenshire County Council's executive board member for public protection, said: "This should be a lesson to anyone who breeds dogs.
"Dylan Huw Thomas deliberately misled his customers and made a lot of money through selling puppies without proper welfare checks and documentation.
"This is a serious crime with serious consequences.
"Breeding and selling without proper licensing, documentation and regard for the welfare and wellbeing of puppies and their mothers will not be tolerated."
Carmarthenshire Council has urged people to ensure they carry out proper checks before purchasing a puppy advertised for sale to avoid funding the illegal dog breeding trade.
They advise that people should see mum and puppy together at the place of breeding, documents should be thoroughly checked, and inquiries should also be made with veterinary practices and local authorities.