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Farm Animal Practice
Johne's disease in sheep and goats
  1. Alastair Greig

    Alastair Greig graduated from the Royal (Dick) School of Veterinary Studies in 1967. After a period in pracitice and research, he joined the Scottish Agricultural College in 1973 as a veterinary investigation officer. Since then, he has developed a particular interest in sheep medicine notably reproduction problems. More recently, he has led a research programme into the epidemiology of Johne's disease in farmed livestock, with particular reference to the role of wildlife. He is currently head of the veterinary science division within the SAC.


JOHNE's disease, or paratuberculosis, is a chronic enteric disease of ruminants and has a worldwide distribution. Economic losses from the disease can be measured in terms of reduced production as well as culled animals. Unlike cattle, in which the disease has been more extensively studied, chronic diarrhoea is not a consistent feature of Johne's disease in sheep and goats; the predominant clinical sign in these smaller ruminants is weight loss over a period of weeks or months. Johne's disease is caused by the bacterium Mycobacterium avium subspecies paratuberculosis. Sheep strains generally fail to grow, or grow only poorly, on routine culture media which support luxurious growth of the organism isolated from cattle. Goat strains tend to be more akin to cattle strains.

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