RESUMO
The disease induced by Bibersteinia trehalosi usually occurs in lambs. It is triggered by certain stress factors and often emerges in the form of severe outbreaks. In adult sheep, only sporadic cases have been reported so far. This paper reports a B. trehalosi-induced high-mortality case occurring only in adult sheep. Seventy out of 628 adult sheep (11%) died in the affected pen during the six days of the outbreak. None of the 146 lambs kept in the neighbouring pen showed any clinical signs during that period. Several preceding events (shearing, vaccination and antiparasitic treatment) can be regarded as factors predisposing to the disease. Five adult sheep (4 females and 1 male) were sent for laboratory examination. Clinical, gross pathological, histological and bacteriological examinations revealed results corresponding to those reported previously in lambs that had died of a B. trehalosi-induced septicaemia.