Cattle's eyes may become new windows to detect mad cow disease

A team of researchers, led by Iowa State University, US, says that the eyes of cattle may reveal signs of neurological disorders such as mad cow disease.

Noticing the symptoms early may help prevent infected meat from getting into the food supply, according to researchers.

The team examined the retinas of sheep infected with scrapie—a disease similar to BSE, or mad cow disease.

They found that sick sheep's eyes had a distinctive 'glow,' reports the BBC.

Jacob Petrich of the department of chemistry at ISU led the study team.

He said that although the research was carried out on sheep, there were hopes that in the future similar procedures could be used to spot symptoms of neurological diseases such as Alzheimer's in humans.

Together with his colleagues, Petrich examined the brain tissue of 73 dead sheep and used standard pathological methods to detect the infectious prion protein.

Once the scientists confirmed that a number of animals were in fact scrapie-positive, they analysed 140 eyeballs by shining a beam of light on the retina, a light-sensitive layer of tissue at the back of the inner eye.

They found that the retinas of infected sheep emitted a characteristic "glow".

"The scrapie-positive retinas fluoresce a lot - they gave a lot of light back, and this light was very structured," said Dr Petrich.

He explained that contrary to the usual way of dissecting the brain in order to analyse the tissue and detect prions, the new technique was an indirect way of looking for a neurological disease.

The study appears in the journal Analytical Chemistry.