Agriculture Minister Edwin Poots has been urged to press for an all-Ireland investigation into concerns about the way former racehorses are being euthanised.
It follows the airing of a BBC Panorama programme, The Dark Side Of Horse Racing, which revealed thousands of animal were sent to slaughterhouses across the UK and Ireland.
Around 4,000 have been slaughtered since the beginning of 2019.
Most were Irish-trained, the programme reported.
SDLP MLA Patsy McGlone said: “I was shocked after watching the programme.
"I could not believe some of the issues raised.
"The way some of these graceful animals are being disposed of is harrowing.”
During the programme it was reported that racehorses killed in British slaughter plants had been transported from Ireland, with some travelling more than 350 miles by road while suffering critical injuries.
It is illegal under Irish and European law to transport a horse in a way that is likely to "cause it injury or undue suffering".
Covert recordings also appeared to show serious breaches of regulations in the slaughter plants.
Mr McGlone added: “I have written to Mr Poots asking that his department fully scrutinise the contents of the programme and establish if any of the issues raised apply to the North.
"I am also calling for a joined-up approach from the Department of Agriculture, Environment and Rural Affairs with their colleagues in the Republic and Britain to fully investigate the concerns raised.”
Yesterday Irish Government officials denied they were aware that "thousands" of ex-racehorses were being sent for slaughter to British abattoirs.
They appeared before the Joint Committee on Agriculture, Food, and the Marine.
The Agriculture Department's deputy chief veterinary officer Michael Sheahan said there were "a few issues" that came up in the programme.
"For me, probably, the most striking issue was around the whole area of horse slaughter," Mr Sheahan told the committee.
Dr Kevin Smyth, assistant secretary general at the department, said he had "no idea" what was happening.