Recurrence of a hairy shaker disease outbreak on an Otago sheep farm

Abstract

The affected farm near Dunedin runs 300ndash;400 breeding ewes with a lambing percent usually around 115ndash;118%. Hairy shaker disease had not been seen on the property until 1983, when there was a major outbreak. In March of that year, the farmer purchased ewes from a number of sources to bring his flock size up to about 400 ewes. As lambing approached, there were a few late abortions, and at lambing about 130 lambs died within a few days of birth, many of them being small and coarse-fleeced (hairy). Two hundred and seventy lambs survived, giving a lambing percentage of 68%. Many of the surviving lambs were hairy and in the next few months most of these developed scours or arthritis and were unthrifty. A diagnosis of hairy shaker disease was made on clinical grounds, and this was confirmed by the culture of the virus from several hairy lambs. It seemed likely that the infection had been introduced with the ewes purchased around tupping time.