Royal Highland Show: Sheep wormer resistance may be worse than first thought

Nematodirus resistance to white drench wormers could be more widespread than initially thought, according to experts.

Until recently it was thought there was no nematodirus resistance to white drenches. However, experts at Moredun Research Institute have confirmed resistance is present in the UK.

See also: More news from the Highland Show

While it is believed resistance is still at low levels, the institute said they could not be sure that was actually the case.

Nematodirus facts

  • Nematodirus parasites live in the intestine of sheep
  • Infection can lead to profuse watery yellow-green scouring and ill thrift
  • Performance of young lambs that receive an early-season check in growth due to nematodirus may be compromised for the rest of the grazing season

Source: Moredun

Speaking to Farmers Weekly, PhD student Lyndsey Melville said: “Resistance could be more widely spread, but we are not quite sure as we have not actually tested for it.

“We know that in certain years when there is acute infection we can see lambs going down very quickly.

“If lambs are not responding to treatment then it could be an indication of a resistance problem.”

Ms Melville said when farmers suspected a resistance problem they should take a dung sample and send it to their vet for testing.

“Over the next three years we are going to be mapping resistance and the genes involved as well as identifying the risk factors,” she said.