The Irish Greyhound Board says it has launched an investigation after 12 dogs were found in cramped conditions at Dublin Port at the weekend.
The animals, who are now in the care of the DSPCA, were discovered in cages on top of each other with no food or water. They were rescued by customs officers.
The DSPCA said that several of the greyhounds had minor injuries and high temperatures. All of them were showing signs of dehydration.
It is believed the dogs were being transported to Spain in a Spanish-registered vehicle.
Condemning what it termed the "barbaric treatment" of the animals, the DSPCA said that paperwork accompanying the dogs showed that all dogs are registered with the Irish Greyhound Stud Book and originate from dog trainers in Cork, Kerry, Tipperary and Wexford. The charity also said records showed that nine of the 12 dogs had raced in the last month, one raced last in 2016 and two have no race records recorded.
DSPCA CEO Brian Gillen said: "This seizure flies in the face of the illusion being created by IGB that animal welfare is being taken seriously.
"The continuing grant of €16.8m of taxpayers money is no longer acceptable."
The IGB says it condemns any mistreatment of greyhounds and will seek prosecution for anyone found to be in breach of animal welfare laws.
In a statement, the IGB said: "The IGB has been made aware this afternoon of an incident at Dublin Port and our welfare department has begun a full investigation.
"The IGB condemns any mistreatment of greyhounds in the highest possible terms.
"Any person or persons found to have been in breach of the Welfare of Greyhounds Act 2011 have been and will continue to be subject to prosecution."