M C Thurmond1, S K Hietala. 1. Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616-8734, USA.
Abstract
OBJECTIVES: To estimate the extent to which abortion risk in dairy cattle during subsequent pregnancies was associated with congenitally-acquired Neospora caninum infection and previous abortions. ANIMALS: 468 Holstein cattle. PROCEDURE: Newborn heifer calves were tested for evidence of congenital infection attributable to N caninum and examined repeatedly until the completion of their second lactation for serologic status and evidence of abortion. RESULTS: Compared with noninfected cows, congenitally infected cows had a 7.4-fold higher risk of abortion during their initial pregnancy and a 1.7-fold higher risk of aborting the first pregnancy during their first lactation. During the first pregnancy of their second lactation, congenitally infected cows that had aborted previously had a 5.6-fold higher risk of abortion, compared with cows that had not previously aborted and that were seronegative. The fetal risk period for N caninum-associated death began sooner and extended later during the initial pregnancy compared with subsequent pregnancies. CONCLUSION: Congenitally acquired N caninum infection can cause a substantial number of abortions during the initial pregnancy of heifers, with abortion risk attributable to N caninum decreasing in subsequent pregnancies, possibly because of selective culling. Subsequent abortions can be expected in congenitally infected cows that have aborted previously.
OBJECTIVES: To estimate the extent to which abortion risk in dairy cattle during subsequent pregnancies was associated with congenitally-acquired Neospora caninum infection and previous abortions. ANIMALS: 468 Holstein cattle. PROCEDURE: Newborn heifer calves were tested for evidence of congenital infection attributable to N caninum and examined repeatedly until the completion of their second lactation for serologic status and evidence of abortion. RESULTS: Compared with noninfected cows, congenitally infectedcows had a 7.4-fold higher risk of abortion during their initial pregnancy and a 1.7-fold higher risk of aborting the first pregnancy during their first lactation. During the first pregnancy of their second lactation, congenitally infectedcows that had aborted previously had a 5.6-fold higher risk of abortion, compared with cows that had not previously aborted and that were seronegative. The fetal risk period for N caninum-associated death began sooner and extended later during the initial pregnancy compared with subsequent pregnancies. CONCLUSION:Congenitally acquired N caninum infection can cause a substantial number of abortions during the initial pregnancy of heifers, with abortion risk attributable to N caninum decreasing in subsequent pregnancies, possibly because of selective culling. Subsequent abortions can be expected in congenitally infectedcows that have aborted previously.
Authors: Aurélie G Andrianarivo; Mark L Anderson; Joan D Rowe; Ian A Gardner; James P Reynolds; Leszek Choromanski; Patricia A Conrad Journal: Parasitol Res Date: 2005-03-15 Impact factor: 2.289
Authors: Devon J Wilson; Karin Orsel; Josh Waddington; Malavika Rajeev; Amy R Sweeny; Tomy Joseph; Michael E Grigg; Stephen A Raverty Journal: Vet Parasitol Date: 2016-01-12 Impact factor: 2.738