Taoiseach Enda Kenny has described the suspected BSE case in Co Louth as "disappointing, to put it mildly".
But Mr Kenny has insisted that Ireland's multi-billion Euro beef exports - including those to newly-opened markets in the USA and China - are not threatened.
Mr Kenny said he had learned of the BSE case from Agriculture Minister Simon Coveney and it had come to light due to the Agriculture Department's rigorous system of monitoring and testing.
"This is an isolated incident and one we're very obviously concerned about," Mr Kenny said.
"It's a disappointment, to put it mildly, given the high level of integrity and credibility we have achieved," the Taoiseach told reporters.
Mr Kenny said contacts in Irish beef markets abroad had been told of the case and they had been fully briefed on all the precautionary measures which were put in place.
He said that in essence Ireland's cattle disease status would not now be upgraded to one of being free from monitoring and this meant the previous monitoring regime will continue. But on the other hand, Ireland's disease rating would not be worsened.
"It's a setback but it puts us back to a situation we were in," the Taoiseach said.
Junior Minister and Co Louth TD Ged Nash also told the Irish Independent that the news of the suspected case of BSE in the county is "disappointing".
He said: "I am due to meet with Department of Agriculture inspectors for a full briefing."
Mr Nash stressed there is no risk to human health as a result of this suspected case.
"While it is disappointing that a suspected case of BSE has been identified in Co Louth, at this point it seems to be an isolated case.
"A full investigation is now under way by the Department of Agriculture and I will be keeping a close eye on these developments," he added.
Giving his reaction to the news, local Fine Gael TD and former minister Fergus O'Dowd said the test results are "deeply concerning" and have potentially serious implications for the country.
Mr O'Dowd said: "This is very worrying and is deeply concerning for the sector."
He said he was contacted by Minister Coveney this morning and that he was reassured that the results came by way of the department's own surveillance system.
Mr O'Dowd also said that it was important to note that the animal in question had not entered the food chain.
He too said he is to get an urgent briefing from the Department of Agriculture.
Another Louth TD, Sinn Féin President Gerry Adams expressed his "very deep concern" at news of a suspected BSE case on a dairy farm in Louth.
He said: "I have written to the Minister for Agriculture Simon Coveney TD asking for all available information about this very serious development."
He added: "While we hope that the tests will be negative, it is imperative that the minister move quickly to provide reassurance to the farming community."