*Treatment/control: isolate aborting ewes; destroy placenta; move other ewes to clean pasture; vaccinate flock with bacterin during outbreak and prophylactically; chlortetracycline in feed in an outbreak | *Treatment/control: isolate aborting ewes; destroy placenta; move other ewes to clean pasture; vaccinate flock with bacterin during outbreak and prophylactically; chlortetracycline in feed in an outbreak |