Finding the ‘hidden iceberg’ is key to beating sheep disease

The monitor farm project is putting its money where its mouth is after calling for commercial sheep farmers to blood test for the often hidden disease of maedi visna (MV) – for which there is no vaccine or cure.

And 20 members of the Border group will see the costs of testing covered by the group in a move designed to highlight how widespread the disease actually is.

Hawick vet Andrew Robinson said his practice had seen a sharp increase in the incidence of MV in the Borders over the past 12 months and believes the disease is seriously underdiagnosed.

“We really need to know the true incidence so that we can advise farmers how to control and eradicate it,” he said. “We would strongly encourage farmers to test their flocks for MV.”

He warned that the disease was a highly infectious and although normally spread by nose to nose contact, it could also spread through colostrum and milk, through the placenta to the unborn lamb and venerally from ram to ewe. “MV is often referred to as an ‘iceberg disease’ because it can take several years before infected sheep show any clinical signs, so the number of animals showing clinical signs are merely ‘the tip of the iceberg’ to the true number of animals that may be infected,” said Robinson.

The clinical signs for MV are varied and include a decrease in scanning percentage, reduced milk production in ewes and lower growth rates in lambs, ill thrift, laboured breathing and increased risk of bacterial pneumonia infection and a higher cull rate.