It’s that time of year again where Nematodirus rears its head, increasing the disease risk for young lambs out at pasture. We wanted to revisit the disease again, because the SCOPS forecast for March and April indicates a moderate to high risk for almost all areas of the UK (see the map below).

Nematodirus becomes a concern at this time of the year due to the increase in temperatures. The Nematode larvae are very resistant to temperature and can survive winter periods within the egg relatively easily. After a cold snap, once temperatures rise over 10ºC for several days, the larvae start to hatch. We don’t normally see this so early on in Spring, especially across the whole of the UK. The recent warm February weather has increased the risk of a mass hatch substantially.

With a severe larval challenge, up to 5% of lambs can die within a few days. Sub-clinically, there will be a negative impact on growth rates meaning a substantial delay to market.

A key sign to look out for is profuse watery diarrhoea. Keep and eye out for staining on the tail and congregation around water. The lambs might also appear dull and depressed, with reduced / no sucking. These symptoms are also similar to cocci, so please ask us if you have any concerns.

Unfortunately for diagnosis, faecal worm egg counts aren’t helpful. This is because the disease is caused by larvae before they start laying eggs.

We would recommend that you give us a call if you have any queries and develop a plan for prevention and treatment.

SCOPS Nematodirus Forecast

Nematodirus Useful Resources