Veterinary practices and sheep farmers are being warned a fatal infection with Nematodirus battus gut worms has been diagnosed in a lamb sent for postmortem at Scotland’s Rural College (SRUC).
The infection – the worms of which live in the intestines – was discovered at the college’s St Boswells Veterinary Investigation centre and causes a severe watery scour that can result in “rapid death”.
Sheep vet at SRUC’s consulting arm Heather Stevenson said: “As these parasites are capable of killing lambs before eggs appear in the dung, any unexplained deaths should be investigated, for example by sending carcases for postmortem.”
According to SRUC, Nematodirus battus worms are a problem in the spring, particularly in years where a cold period is followed by a warm spell. The newly discovered case reflects the rise in spring temperatures that has triggered hatching of eggs in some areas.
After hatching, the worms are eaten along with grass and pose a threat to lambs from 6 to 12 weeks old. Outbreaks of disease are most common on fields grazed by young lambs every year in the spring. Those particularly at risk are lambs born in February or March and grazing permanent and heavily stocked pastures.
SRUC is urging farmers to take appropriate action to prevent disease outbreaks as soon as possible and investigate cases of severe diarrhoea in lambs with the help of their own vets or experts.
More information on Nematodirus hatching times can be found on the SCOPS website, where a colour coded map indicates the disease risk by region.
SRUC said when risks are high, lambs should be treated with an appropriate wormer from six weeks of age to prevent disease. It is important farmers take advice on which product to use, it said, and if resistance is suspected, dung samples should be checked for eggs 10 days after treatment.