Sheep version of MCD- Scrapie or Johanne's Disease??

Scrapie is the disease most like Mad Cow (BSE,MCD) and is a prion based infection. Johnes, is a bacterial infection of the gut by the same bacteria that causes TB in humans. In cattle the Johnes will cause obvious distress, watery foul diarrhoea, etc. in sheep it's not always obvious. This may be where you're getting confused as it can be a chronic wasting type disease. If your sheep are eating well and are not infected with worms, you could test for Johnes. Scrapie wasting is due to not eating. Scrapie infected sheep don't always show many symptoms, odd behavior or trouble controling how they walk (a peculiar hopping gate not related to feet problems) are common symptoms. If your sheep are healthy good producing animals I'd be surprised to hear they had either disease.

Regarding Johnnes', I would say that it IS obvious, same symptoms as cattle. They get the runs and they drop body weight very fast, even though they still eat. This is after worms and other intestinal problems have been ruled out. We had what seemed to be this disease affect a friend's small flock of barbado sheep that were being boarded at our place. Our wool sheep have never shown the slightest sign of illness and it's been over 3 years now. Johnnes' is very difficult to diagnose, the sick sheep came from a flock that was tested over and over again, and they got 1 positive result after many negative ones.

What is even more scary, as it can take up to 10 years for a sheep to show visiable signs of the disease.

It is best to be in the Scrapie program.