Naturally occurring scrapie in southdown sheep

The purpose of this study was to characterize naturally occulting scrapie i n the Southdown breed of sheep. Experimental subjects included 4 Southdown ewes admitted to the University of Missouri, College of Veterinary Medicine Large Animal Clinic. All 4 sheep had signs compatible with clinical scrapi e. Cerebrospinal fluid (CSF) cell counts ranged from a low of 1 nucleated c ell/mu L to high of 4 cells/mu L, with a median of 3 cells/mu L. Cerebrospi nal protein concentrations ranged from 26 to 78 mg/dL with a median of 53 m g/dL. Immunoassay of the CSF for the 14-3-3 protein yielded positive result s in 3 of the 4 sheep. Sequencing of the prion protein (PrP) gene revealed that an 4 sheep were homozygous for glutamine at codon 171 and, hence, were of the QQ genotype, Histopathologic examination of brain stem tissue secti ons revealed intracytoplasmic neuronal vacuolation and mild spongiform chan ges in the gray matter neuropil in all 4 ewes. The diagnosis of scrapie was confirmed by immunohistochemical staining for the abnormal PrP. Our result s suggest that the,genetics of scrapie susceptibility are probably similar in Suffolk and Southdown sheep. Positive immunoassay results for the 14-3-3 protein were observed in 3 of the 4 sheep.