Thursday, 23 May 2013

Killer parasites threat to lambs

SAC vets are warning that parasitic worms are hatching earlier this year, putting lambs at risk of the potentially fatal digestive irritation they cause.

andy lambsinfield
Parasitic worms are hatching earlier this year

Sheep farmers are being urged to select the appropriate anti-worm treatment and investigate any unexplained lamb deaths with the help of their vets and SAC.

Nemotodirus battus worms are a particular problem in the spring, especially after a cold period is followed by a warm spell and there is a mass hatch onto grass pasture.

The immature worms can cause sudden death or a watery diarrhoea which leaves weakly “unthrifty” lambs.

This can leave them susceptible to another parasite, causing coccidiosis and kidney damage, increasing losses.

N battus eggs are resistant to the elements and survive very cold winters so this year’s temperatures have been particularly kindly. A hatch is expected this month, posing a threat to six-week-old lambs all over Scotland.

Dr George Mitchell of SAC consulting veterinary services said: “Permanent and heavily-stocked, low-ground pastures are particularly at risk”.

“If the nemotodirus hatch continues into June, hill lambs on improved pasture which are relatively heavily-stocked may be affected. The parasite can kill lambs before the eggs appear in the dung so any unexplained deaths should be investigated.”

When risks are high, SAC recommend treating lambs with the appropriate “anthelmintic” wormer from six weeks old. As the rise in worm numbers is rapid, two doses, seven to 10 days apart, are advised.

It is important farmers take advice on which one to use because on some farms there is evidence the nemotodirus are resistant to some treatments. If it is suspected, dung samples should be checked for worms 10 days after treatment.

SAC offers a wormscan service on pooled dung samples to reduce cost. Details are available from SAC veterinary centres. For more information contact Brian Hosie on 0131 535 3140, 07803 222 366 or email brian.hosie@sac.co.uk.

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