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  • Author or Editor: G. Reed Holyoak x
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in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association


Correlation between serum testosterone concentration and morphometric findings from ultrasonography of the accessory sex glands in peripubertal colts was investigated during pubertal development. Nineteen colts of initial age ranging from 5 to 12 months were monitored over a 13-month period. Serum testosterone concentration was determined on a biweekly basis, and accessory sex gland development was ultrasonographically monitored once a month. Notwithstanding individual variation, there was significant correlation (r = 0.913; P < 0.01) between increasing serum testosterone concentration and the onset of developmental changes involving the accessory sex glands. As colts entered their 2-year-old year with relatively immature reproductive tracts, compared with mature stallions, there was still a significant seasonal effect on serum testosterone concentration and accessory sex gland measurements (P < 0.05). Ultrasonography was confirmed as a valuable noninvasive method of monitoring and assessing peripubertal accessory sex gland development in colts.

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in American Journal of Veterinary Research


Objective—To determine whether it is safe to vaccinate pregnant or postpartum mares with a commercial modified-live virus vaccine against equine viral arteritis (EVA).

Design—Randomized controlled study.

Animals—73 mares and their foals.

Procedures—Mares were vaccinated during mid gestation, during late gestation, or 2 or 3 days after parturition with a commercial modified-live virus vaccine or were not vaccinated. Foaling outcomes were recorded, and serum, blood, milk, and nasopharyngeal samples were obtained.

Results—All mares vaccinated during mid gestation foaled without any problems; 21 of 22 mares in this group had antibody titers against EAV at the time of foaling. Of the 19 mares vaccinated during late gestation, 3 aborted; antibody titers against EAV were detected in 13 of 15 mares from which serum was obtained at the time of foaling. All postparturient vaccinates were seronegative at foaling; all of them seroconverted after vaccination. No adverse effects were detected in any of their foals.

Conclusions and Clinical Relevance—When faced with a substantial risk of natural exposure to EAV, it would appear to be safe to vaccinate healthy pregnant mares up to 3 months before foaling and during the immediate postpartum period. Vaccinating mares during the last 2 months of gestation was associated with a risk of abortion; this risk must be weighed against the much greater risk of widespread abortions in unprotected populations of pregnant mares naturally infected with EAV.

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in Journal of the American Veterinary Medical Association