That cow with the gleam in her eye isn’t angry because you are standing between her and her calf. She’s “mad” for another reason.
Iowa State University and the National Animal Disease Center in the United States found that sheep with scrapie, another prion disease like bovine spongiform encephalopathy (BSE), have a distinct fluorescence in their retinas. Scientists believe it is an accumulation of a substance called lipofuscin. The results of the research need to be confirmed. A non-invasive test conducted while the animal is still alive, means that slaughtering an entire herd, as is done now when BSE is found in an animal in Canada, is unnecessary.