BSE is an untreatable neurodegenerative disorder, which incubates for years before symptoms are obvious and is usually only discovered when the animal can no longer stand on its own. It is caused by misfolded brain proteins known as prions.
Heather Greenlee, an associate professor of biomedical sciences in Iowa State’s College of Veterinary Medicine, said 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 said. "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 the peer-reviewed academic journal PLOS ONE.
The experiments involve electroretinography and optical coherence tomography, non-invasive technologies commonly used to assess the retina. Greenlee said cows infected with BSE showed marked changes in retinal function and thickness.
Greenlee said the results had implications for food safety, and 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.
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, she claimed. "Our goal is to develop our understanding of the retina to monitor disease progression and to move diagnoses up earlier," Greenlee said. "We think this research has the potential to improve diagnosis for a range of species and a range of diseases."