Gardaí are investigating the discovery of at least six greyhound carcasses found dumped at a disused quarry in Limerick.
It is believed the dogs, found in Ballyagran, were shot in the head.
Racing greyhounds are required to have an identifying tattoo in each ear and some of those were still legible.
The Irish Greyhound Board, Bord na gCon, says it has identified two owners and is working with gardaí to bring the offenders to justice.
Bord na gCon Welfare Officer Barry Coleman said the killing of the dogs contravened the new Greyhound Welfare Bill.
The Greyhound Rescue Association of Ireland said that there were nearly 3,500 registered greyhound litters in Ireland last year, and that up to 10,000 disappear every year in this country.
The GRAI says these dogs make ideal family pets and do not need to die.
Bord na gCon is urging owners to keep or re-home retired racing greyhounds, and is working with the Irish Kennel Club to put a number of initiatives in place.