Local tissue reaction to the administration of an inactivated Brucella ovis saline-in-oil vaccine by the intraperitoneal route

An inactivated Brucella ovis saline-in-oil vaccine was administered to 14 adult ewes using both the intraperitoneal route and the subcutaneous route. Pairs of animals were necropsied at intervals between 24 hours and ten weeks after injection. The nature of the local inflammatory reaction to the administration of the vaccine was similar at all sites. The lesion consisted of granulomatous inflammation arranged around droplets of oily vaccine. Diffuse peritonitis was seen at necropsy in 12 of the 14 animals. A local extraperitoneal inflammatory response at the injection site was present in four animals despite careful attempts to deposit the vaccine within the abdominal cavity. A second study of 30 rams vaccinated by the intraperitoneal technique confirmed that extraperitoneal deposition of vaccine commonly occurred and that approximately 20% of animals vaccinated by the intraperitoneal method still had peritonitis six months later.