Winter Dysentry

Author: Richard Laven PhD BVetMed MRCVS
Published: 2001

What is Winter Dysentery?

Winter dysentery is an infectious disease that affects all ages of cattle. It is extremely infectious with up to 100% of cattle being affected, but death is very rare. Its cause is unknown but acoronavirus is the current favourite.

Clinical Signs

  • Severe, watery, foul-smelling dark brown diarrhoea
  • The diarrhoea may be explosive
  • There may be some blood in the faeces
  • Usually seen in one or two cattle at first, but spreads rapidly, with most older cattle being affected within two weeks
  • Appetite is usually normal, but milk yield may be reduced by 50%
  • Usually lasts two to three days


  • On the clinical signs described above
  • Initial cases may look like a poisoning or feed problem, but rapid spread and severity (without death) makes diagnosis relatively easy
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  • No effective treatment, and most cows recover within three days
  • If dehydration occurs then electrolytes (by mouth or by vein if very severe) are essential


1) The disease  may be brought on farm by outside personnel, such as veterinarians, consultants, hoof trimmers, and representatives. So ensure that such staff are clean prior to entry

2) Bought-in cattle are also an important source of disease

3) If an outbreak occurs, no cattle or unnecessary personnel should enter the farm and strict disinfection should occur before anybody leaves the farm

4) After an outbreak, herd immunity tends to reduce the risk of another outbreak for about five years


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