Multiple cases of maedi and visna in a flock in East Anglia
Pritchard, G.C.; Done, S.H.; Dawson, M.
Veterinary Record 137(17): 443
1995
ISSN/ISBN: 0042-4900 PMID: 8560707 Document Number: 448897
In August 1995, two aged mule ewes in fairly poor condition and blind (one bilaterally and the other unilaterally) were examined. The ewes came from a commercial flock of 1200 ewes (mainly Scottish and North Country mules) in East Anglia, UK, which appeared to have had at least 30 cases of either maedi or visna during the past year. PM examination identified typical gross lesions of maedi in one ewe. Histological lesions characteristic of visna were present in both ewes as well as lymphoid aggregates in udder, joint capsules and lungs which also showed interstitial pneumonia and characteristic smooth muscle hyperplasia. Examination of serum samples from 40 ewes in the flock in 1995, showed that 80% were seropositive for maedi visna virus infection, this compared with a seroprevalence of 34% when the flock was examined in 1985. The importance of these findings to the UK sheep industry is discussed.