Objective—To determine whether administration of
killed West Nile virus vaccine was associated with
pregnancy loss among broodmares.
Design—Retrospective cohort study.
Procedure—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 and Clinical Relevance—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. (J Am Vet Med Assoc 2004;225:1894–1897)
Objective—To determine whether the concentrations of airborne virulent Rhodococcus equi in stalls housing foals during the first 2 weeks after birth are associated with subsequent development of R equi pneumonia in those foals.
Sample—Air samples collected from foaling stalls and holding pens in which foals were housed during the first 2 weeks after birth.
Procedures—At a breeding farm in Texas, air samples (500 L each) were collected (January through May 2011) from stalls and pens in which 121 foals were housed on day 1 and on days 4, 7, and 14 after birth. For each sample, the concentration of airborne virulent R equi was determined with an immunoblot technique. The association between development of pneumonia and airborne R equi concentration was evaluated via random-effects Poisson regression analysis.
Results—Some air samples were not available for analysis. Of the 471 air samples collected from stalls that housed 121 foals, 90 (19%) contained virulent R equi. Twenty-four of 121 (20%) foals developed R equi pneumonia. Concentrations of virulent R equi in air samples from stalls housing foals that developed R equi pneumonia were significantly higher than those in samples from stalls housing foals that did not develop pneumonia. Accounting for disease effects, air sample concentrations of virulent R equi did not differ significantly by day after birth or by month of birth.
Conclusions and Clinical Relevance—Exposure of foals to airborne virulent R equi during the first 2 weeks after birth was significantly (and likely causally) associated with development of R equi pneumonia.