NY Times article on CWD

Wasting-Disease Culprit May Be Tongue?

http://www.nytimes.com/2005/10/04/science/04tong.html

Although it's a nice discussion about how prions might move around within an animal, I definetely think shedding of prions by faeces or urine onto feed, and then consumption of contaminated feed is much more likely a route of transmission among animals, not sloughing of tongue skin cells.  I wouldn't discount saliva though.  Even infected carcasses could be a transmission route (see paper by Miller et al.).