Internal Parasites of Sheep:
Nematode worms are an ever-present hazard to grazing sheep. They come in a variety of different types:
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Blood sucking worms that live in the stomach causing anaemia and even sudden death in all ages of sheep
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Intestinal worms that live in the stomach and intestines, causing diarrhoea, loss of weight and eventual death in growing lambs
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Lungworms that live in the lungs. contributing to coughing and pneumonia in growing lambs
Nematode worms are normally controlled by using anthelmintic drugs (wormers), of which there are numerous different products on the market. The choice of wormer may be critical to your enterprise and advice should be sought, rather than just buying the one on "special offer".
Trematode worms (Flukes) live in the bile ducts and gall bladder of sheep. They cause liver damage and anaemia in all ages of sheep and require specialist treatments for their control. If you have or suspect fluke, then you should seek specialist advice from Larkmead. For further information on fluke in sheep, read this article by NADIS. Liver fluke in sheep.
Cestode worms (Tapeworms) that live in the small intestine. Although the sheep tapeworm is generally considered to be harmless in adult ewes, they may cause diarrhoea and loss of weight in lambs under 6 months.
NOTE: Dog and fox tapeworms pass segments that can cause damage to sheep if they are ingested. Although these segments do not develop into adult tapeworms in the sheep, they migrate through the tissues of various organs. Some species migrate through the liver, causing liver condemnations that can be mistaken for fluke infection at slaughter. One species of dog tapeworm migrates to the brain of sheep, causing the disease known as “gid”. It is very important to keep all sheep dogs well wormed for tapeworms using an effective product such as Drontal Plus. Do not feed dogs on raw sheep offal, for fear of perpetuating the tapeworm life-cycle.
Coccidia are unlike the above, in that they are not helminth worms, but protozoa. They live in very large numbers in the small and large intestines of sheep, and can cause diarrhoea and growth retardation in lambs of up to 10 weeks of age. The normal anthelmintic drugs do not control coccidia and specialist medicines are required. If you have scouring lambs that do not respond to normal anthelmintic treatment, you may have a coccidiosis problem and should consult Larkmead.
Treatments
The treatment of all of these different types of internal parasites is very complex, and there is no single medication that can deal successfully with all of them. To further complicate matters, many of these parasites have become resistant to the effects of some anthelmintics, making their control even more difficult.
The sheep advisory service of Larkmead Veterinary Group can help by advising on a farm worming protocol to obtain maximum returns from your anthelmintic expenditure. This may include analysing faecal samples to determine optimum dosing times and testing for evidence of anthelmintic resistance to advise on the correct product to use. Our advice on worming policy could save you a considerable annual expenditure on wormers.
For detailed information on anthelmintic resistance and the Sustainable Control of Parasites in Sheep (SCOPS), go to: www.nationalsheep.org.uk/images/stories/pdf/WormControl_BW.pdf
Read the NADIS Sheep Bulletin, sponsored by Eblex, covering Anthelmintic Resistance on Sheep Farms.
Try this quiz to test your knowledge of the condition..........NADIS Quiz
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Last Updated : 04 March 2009 (C) Larkmead Veterinary Group Ltd.