In recent research, it was discovered that disease-associated prion protein accumulates in the lymphoid tissue of the rectal mucosa in a high percentage of scrapie-infected sheep. Rectal biopsies have the advantages of providing high numbers of lymphoid follicles for testing and are considered to be relatively easy to perform.
The intent is that the rectal biopsy will be used for all of the same purposes as the third eyelid test. With a sensitivity level reaching into the 87th percentile for detecting scrapie-positive sheep, the rectal biopsy is proving to be as effective as the third eyelid test. It is also anticipated that there will be a lower risk of receiving a 'no-test' result."This newly approved test is as good or better for diagnosing scrapie in live sheep and goats than the third eyelid test for a number of reasons," stated Diane Sutton, DVM, coordinator for the National Scrapie Eradication Program. "It is less invasive and less stressful for the animal so producers should like it better, and it is a faster and easier test to perform for the veterinarian."
The rectal biopsy is currently only being used by USDA and state personnel for scrapie testing but is expected to be available to accredited veterinarians in the future after training and guidance have been provided.
Source: ASI Weekly, March 21, 2008
