This is a chronic, debilitating disease that occurs in sheep as well as goats, cattle, alpacas and deer. It is caused by Mycobacterium paratuberculosis and the disease is usually mild in sheep but under certain conditions there may be significant losses. Transmission of Johnes disease is via the faecal-oral route although intrauterine infection also occurs. There appears to be little spread of infection between sheep and cattle but goats and deer may act as a source of infection for sheep and cattle. Young lambs are more susceptible to infection but because of the long incubation period, it is more common to see clinical infection in older sheep. The most common sign is weight loss but affected animals will usually have a normal appetite until the terminal stages. Death occurs from a few weeks to months. Blood samples are the best means of diagnosing Johnes disease. Faecal culture is also possible but can take several months to yield results. Once the disease has established itself on your farm you are unlikely to eradicate it because of the bacterias ability to survive for long periods on the pasture, the long incubation period and the difficulty in testing for carrier animals. There are measures that you can take to minimise losses: Test and slaughter policy. Isolation of suspect animals. Heavy culling of older ewes. Culling any suspect cases well before lambing time. Place water troughs on higher ground and fence off areas becoming contaminated and muddy. Vaccinnes are available. Ask your vet for advice.