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THERE have been several reports of ulcerative balanitis and vulvitis occurring in sheep flocks in the uk and elsewhere. Greig (2007) divided them into four main entities: venereal parapoxvirus (orf) infection; enzootic posthitis (pizzle rot) caused by Corynebacterium renale or other diptheroid organisms; a mycoplasma-associated vulvovaginitis (related to Mycoplasma mycoides subspecies mycoides ); and a condition of unknown aetiology. Other organisms variously isolated from the lesions have included Streptococcus zooepidemicus ( Dunn 1996 ), Histophilus ovis, Actinomyces pyogenes and the mycoplasmas, Mycoplasma fermentans and Mycoplasma bovigenitalium (formerly Mycoplasma ovine group 11) ( Nicholas and others 1998 , Ayling and others 2004 ). This paper describes three outbreaks that were investigated during the autumn and winter of 2006, including a particularly severe outbreak in a lowland flock in East Anglia from which ovine herpesvirus type 2 ( ohv-2 ) was detected in blood and vulval and penile lesions.
MATERIALS AND METHODS
Case histories
Flock 1 The outbreak began in late October 2006 in a long established 450 ewe commercial lowland flock of Suffolk mules and Texel crosses in coastal Suffolk. The sheep were grazing on 100 acres of permanent marshland pasture in an isolated location, and had no direct contact with other livestock, apart possibly from feral deer. A herd of 420 suckler cows was kept on another part of the farm, and the sheep sometimes grazed on the same pasture after the cattle, but the only time they may have been in direct contact was when they were housed during lambing. About 25 to 30 per cent of the breeding flock was replaced each year (by shearlings) but the only animals added during the previous four months were five shearling Suffolk rams purchased from a single flock in south-east England through a livestock dealer. These arrived at the beginning of October and were immediately mixed with the six resident rams and subsequently put in with the ewes without going through a quarantine period.
After the rams had been serving the ewes for three weeks, one of the purchased rams was observed by the owner to have a bleeding and swollen penis and was promptly separated from the group and not used again. Ten days later the owner noticed that several ewes had developed swollen vulvas,...