Nematodirus Update: CASES
SEEN - April 2016
Earlier this week 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
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
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 if you would like to discuss what samples to collect.