Evaluation of administration of West Nile virus vaccine to pregnant broodmares.
OBJECTIVE
To determine whether administration of killed West Nile virus vaccine was associated with pregnancy loss among broodmares.


METHODS
Retrospective cohort study.


METHODS
595 mares.


METHODS
Records of pregnant mares with known vaccination history from 4 farms were reviewed. Information obtained from 595 mares included mare's identification; farm; age; breed; reproductive status; last breeding date; date last known pregnant; vaccination date; age of conceptus at vaccination; vaccination during the early embryonic, early fetal, and late fetal periods; and whether an early embryonic death (EED), early fetal loss (EFL), or late fetal loss (LFL) occurred. The relationships between the dichotomous outcomes of loss (eg, EED, EFL, LFL) and independent categoric variables (eg, vaccination during the early embryonic, early fetal, or late fetal periods) were examined.


RESULTS
Vaccination of pregnant mares during any period of gestation was not associated with increased incidence of pregnancy loss.


CONCLUSIONS
Many mares are already pregnant at the onset of mosquito season, when mares are more likely to be vaccinated than at other times. Our findings provide evidence that vaccine administration will not compromise pregnancy in horses.
Vest
Dickie J
DJ
Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A & M University, College Station, TX 77843-4475, USA.
Cohen
Noah D
ND
Berezowski
Christopher J
CJ
Morehead
James P
JP
Blodgett
Glenn P
GP
Blanchard
Terry L
TL
D000818:Animals; D015331:Cohort Studies; D005260:Female; D005313:Fetal Death / Q000453:epidemiology / Q000662:veterinary; D006734:Horse Diseases / Q000517:prevention & control*; D006736:Horses / Q000502:physiology*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000662:veterinary*; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D014765:Viral Vaccines / Q000008:administration & dosage* / Q000009:adverse effects; D014901:West Nile Fever / Q000517:prevention & control / Q000662:veterinary*; D014902:West Nile virus / Q000276:immunology*
D014765:Viral Vaccines