Retina scans could spot ‘mad cow’ faster

"Our goal is to develop our understanding of the retina to monitor disease progression and to move diagnoses up earlier," says Heather Greenlee. (Credit: omcoc/Flickr)

Examining eyeballs could be a faster way to detect the fatal neurological disease called “mad cow,” report researchers.

Bovine spongiform encephalopathy (BSE), known more commonly as mad cow disease, is an untreatable neurodegenerative disorder caused by misfolded brain proteins known as prions.

Classic BSE incubates for years before producers or veterinarians notice symptoms of the disease, which is usually discovered when the animal can no longer stand on its own.

But Heather Greenlee, an associate professor of biomedical sciences in Iowa State University’s College of Veterinary Medicine, says studying the retinas of cattle can identify infected animals up to 11 months before they show signs of illness.

“The retina is part of the central nervous system,” Greenlee says. “Essentially, it’s the part of the brain closest to the outside world, and we know the retina is changed in animals that have prion diseases.”

In collaboration with Justin Greenlee’s group at the US Department of Agriculture’s National Animal Disease Center, she recently published findings in PLOS ONE.

The experiments involve electroretinography and optical coherence tomography, noninvasive technologies commonly used to assess the retina. Greenlee says cows infected with BSE showed marked changes in retinal function and thickness.

Deer and people, too?

The results have implications for food safety, and Greenlee says the screening methods used in her research could be adopted for animals tagged for import or export as a means of identifying BSE sooner than conventional methods.


Greenlee says she’s also looking at how similar diseases in other species affect the retina. For instance, she’s conducting experiments to find out if retinal tissue may be a valid means of surveillance for chronic wasting disease in deer.

She says she isn’t ready to publish her results, but the data gathered so far looks promising.

The research also may contribute to faster diagnosis of Alzheimer’s disease and Parkinson’s disease in humans, both of which are caused by proteins folding incorrectly.

“Our goal is to develop our understanding of the retina to monitor disease progression and to move diagnoses up earlier,” Greenlee says. “We think this research has the potential to improve diagnosis for a range of species and a range of diseases.”

Source: Iowa State University