Two outbreaks of BSE are being investigated by the Department of Agriculture.
One of the cases involves a 5-year-old dairy cow in Co Meath.
The outbreak is of concern as it comes after stringent measures to combat BSE were introduced in the mid 1990s.
The second case identified this week involves an 11-year-old dairy cow in Cork.
BSE has caused huge damage to the Irish beef industry over the past 15 years.
Irish beef exports were banned from many countries and a hugely expensive series of Government measures were put in place to deal with the disease.
The two cases this week bring the total for the year so far to 17.
The total number of confirmed cases in 2007 was 25. This compares with 41 in 2006, 69 in 2005, 126 in 2004, 182 in 2003 and 333 in 2002.
