Gut Worms

The NADIS disease forecast is based on detailed Met Office data, and regional veterinary reports from 37 farm animal practices and the large animal units at six UK veterinary colleges.

NADIS data can highlight potential livestock disease and parasite incidences before they peak, providing a valuable early warning for the month ahead.

NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare. Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.

December 2004

Richard Laven BVetMed MRCVS


NADIS Cattle Disease Focus

Gut Worms (Parasitic Gastroenteritis or PGE)

Warm moist summers and autumns are ideal for gut parasites as they can reach higher peak numbers and stay near those numbers for longer.

In cattle the primary effect of gut worms is poor growth (or weight loss) with diarrhoea, death is rarer in cattle than sheep. Controlling worms is thus important in cattle, particularly in youngstock, and should form an integral part of your herd health plan.

It is also important to be aware of the rising problem of resistance in worms, particularly those found in sheep, and to use all wormers carefully to minimise the risk of resistant worms being found on your farm.
 Clinical Signs

  • Diarrhoea – often green and profuse
  • Weight loss
  • High proportion of animals affected

There are two main seasons for gut worm problem in cattle, July to November and February to May. In the summer/autumn the problems are caused by worms picked up from the pasture; in the winter, most, but not all, cases are caused by larvae which have hibernated in the calf‘s stomach reviving and resuming their development.


  • Worm egg count – collect ten faecal samples as fresh as possible and send them to your vet or lab. They will bulk them together and give you a WEC. Several samples are important, as not all animals will have high WEC‘s.
  • Other blood tests may be useful such as pepsinogen or minerals to rule out additional problems.
  • PM – these can be extremely helpful in confirming a diagnosis.

Treatment & Prevention
Prevention is far more cost effective than treatment; planning worm control can thus save significant amounts of money.

For most farms wormers will still be an essential part of economic stock production, so strategic wormer use needs to be built into the worm control plan. Each individual farm should have its own individual worm plan, based on farm management, previous worm history and type of stock. Nevertheless there are several factors to bear in mind when developing the plan:

  • Use pasture effectively so that cattle avoid grazing contaminated pasture during the peak season. This can be as simple as moving cattle onto fresh ungrazed pasture (such as silage aftermath) just before the summer rise in larval numbers.
  • Reduce routine worming by monitoring, particularly WEC and growth. This will save you money and reduce the risk of resistance developing on your farm.
  • Worm at housing in stock susceptible to hibernating larvae
  • Don‘t forget lungworm control; this is an increasing problem on many farms. Control measures such as pasture management are less effective for lungworm than gut worms, so use vaccination to control lungworms.

While every effort is made to ensure that the content of this forecast is accurate at the time of publication, NADIS cannot accept responsibility for errors or omissions. All information is general and will need to be adapted in the light of individual farm circumstances in consultation with your veterinary surgeon

Copyright © NADIS 2002

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