Epizootic Bovine Abortion.
Epizootic bovine abortion, or Foothill Abortion, appears to be geographically limited to the western United States. Live fetuses may be aborted, and most dead fetuses are fresh. Fetal lesions include granulomatous hepatitis and lymphoid hyperplasia in the lymph nodes. Once a heifer or a cow aborts and remains in the area she will be immune.
Drost M (1969)