Why do sheep sometimes spontaneously become sick and die?

[kethinov]

I have seen this from time to time:

*has become infected with scrapie*
* a sheep begins to spasm uncontrollably *

What's up with that? I kinda wanna run and cast cure whenever I see it, but they die so fast!

 

[IndecentXp0sur3]

The start of the zombie apocalypse

 

[Bromista]

I think it's to keep people from trapping them to macro farming their wool