Department of Agriculture vets found 5,001 lesions on cattle previously deemed free from bovine TB at their last herd test over its post-slaughter carcase inspections in 2023, according to the All-Island Animal Disease Surveillance Report for that year.

Further testing revealed that just over half of these lesions tested positive for TB, representing 2,559 cattle not known to have the disease when sent for slaughter.

This testing is carried out as not all lesions in pulmonary and lymph node tissues are caused by the bacteria behind bovine TB - Mycobacterium bovis.

The replacement of culture testing with PCR testing for lesion samples which deliver inconclusive results in the first round of lab lesion testing “significantly decreased turnaround times” for farmers hearing word on the results of lesion testing.

Tissue samples

The report also states that 2023 saw 1,103 badger tissue samples tested for TB in Department labs, with just under one-third of these returning bovine TB-positive results, but that this result does "not reflect prevalence of bTB in the wider animal population, rather, they represent prevalence within a subset of suspected bTB cases".

The Department of Agriculture, Animal Health Ireland and Northern Ireland’s Agri-Food & Biosciences Institute all contribute to the animal disease surveillance report.