A builders' merchant has pleaded guilty to burying dead greyhounds at his County Durham home without a licence.
David Smith buried the animals near his home
David Smith, of Northdene Terrace, Seaham, appeared before magistrates at Durham, after the Environment Agency opted to bring a private prosecution.
Last July it was claimed Mr Smith shot about 10,000 dogs with a bolt gun.
The case was referred to crown court for sentencing, where he could face an unlimited fine or five years in jail. He was granted unconditional bail.
Mr Smith received death threats when he was accused of slaughtering thousands of animals using a bolt gun, then disposing of the carcasses behind his home.
He was questioned by police, but it was confirmed the bolt gun used to kill the retired greyhounds was held legitimately.
Inquiries by the RSPCA concluded that there was no indication animal cruelty laws had been broken, because the dogs had been killed humanely.
However, following a six-month investigation, the Environment Agency said it was taking out a private prosecution against the father-of-three under regulations usually used to restrict the dumping of waste.
Mr Smith faced a single charge under the Pollution Prevention and Control (England and Wales) Regulations that, on July 12 2006, he disposed of waste, namely the bodies of deceased dogs, on land without a permit.
It was alleged he could have killed and buried up to 10,000 greyhounds at £10 a time, but the magistrates heard that the number was "substantially less" although no precise figure could be determined.
The regulations, introduced in 2000 following an EU directive, were designed to reduce or prevent emissions to air, land or water, and a breach of the regulations can result in a heavy fine or even prison.