WE would like to raise our concerns with veterinary colleagues over an apparent increase in the number of flocks in the maedi visna (MV) accreditation scheme that have had a breakdown with MV infection. Most of the blood testing for the MV accreditation scheme takes place during the summer months; however, so far this year there have been nine breakdowns with MV infection in accredited flocks and a further five flocks have had positives at qualifying tests. We first highlighted an increase in MV breakdowns in 2010 when there were 13 (Ritchie and Hosie 2010). Since then there have been between five and eight breakdowns each year in MV accredited flocks from the 2600 flocks in the scheme. In the most serious breakdown this year over 90 per cent of the adult sheep were found to be infected with MV. It is now a salvage operation to try to save some of the genetics in the flock by collecting embryos from some of the more valuable ewes before the flock of 120 high value, pedigree sheep and their offspring are culled. The flock …