EVALUATION OF ABORTIONS IN CATTLE ATTRIBUTABLE TO NEOSPOROSIS IN SELECTED DAIRY HERDS IN CALIFORNIA

Objective-To estimate the minimum rate of abortion attributable to inf ection with Neospora sp in selected California dairy herds. Design-Pro spective study. Animals-Twenty-six dairy herds containing 19,708 cows were studied. Fourteen herds had a history of abortions attributable t o neosporosis, and 12 were herds in which neosporosis had not been ide ntified as a cause of abortions. Procedure-During a 1-year period, all available aborted fetuses were submitted to veterinary diagnostic lab oratories to determine the cause of abortion. Reproductive records of cows that aborted were reviewed. Results-Neospora sp infection was the major cause of abortion identified (113/266 abortions, 42.5%). The ma jority (232/266, 87.2%) of the aborted fetuses were submitted from her ds with a history of abortions attributable to neosporosis, and Neospo ra sp infection was identified as the causative agent in 101 of 232 (4 3.5%) of the abortions from these herds. Fewer aborted fetuses were su bmitted from the 12 herds that did not have a history of abortion attr ibutable to Neospora sp; however, neosporosis was confirmed as a cause of abortion in 6 of these 12 herds and was identified as the causativ e agent in 12 of 34 (35.3%) abortions from these herds. The disease wa s widespread throughout the state (19/26 herds in our study). Availabl e reproductive histories of cows that had abortions attributed to neos porosis were evaluated, and 4 cows were identified that twice aborted Neospora-infected fetuses.