Nematodirus Update from the SAC: CASES SEEN

Nematodirus Update from the SAC: CASES SEEN

Earlier this year post mortem examination of a 20kg lamb at the Dumfries centre revealed scour, around 8,000 nematodirus worms in the small intestine and 250 nematodirus eggs per gram (epg).  On the same day our Ayr centre reported nematodirus results of 1,250 to 1,800 epg in samples received from eight-week-old scouring lambs.

These are the first nematodirus reports of the season for South West Scotland.

The SCOPS nematodirus forecast map is still showing a low risk for this area i.e. temperatures have been within the hatching range but hatch is not imminent.  There will however be farm to farm and field to field variation depending on aspect, altitude and grazing history.

With only one confirmed case of resistance, (in Cumbria), SCOPS advice is that benzimidazole anthelmintics remain an appropriate choice for the prevention and treatment of nematodirosis on most farms.  This should be reviewed if worm egg counts indicate concurrent infection with other trichostrongyloid worms (most likely Teladorsagia sp.) in which benzimidazole resistance is widespread.   For example the faecal samples tested at Ayr also contained 100 to 500 strongyle type eggs per gram.  The pre patent period of N. battus is around 14 days, so if you want to check treatment efficacy, post dosing samples should be collected after 7 to 10 days.

N. battus is the dose limiting parasite for many anthelmintics so it is important that good dosing practice is followed to avoid under dosing.  A poor response to treatment should trigger further investigation and could be due to concurrent coccidiosis or the development of nephrosis secondary to intestinal damage.  Please get in touch  with our farm department on 01746 713911 if you would like to discuss what samples to collect.

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