Potential differences between Leptospira serovars, host-adapted (Bratislava) and incidental (Copenhageni), in determining reproductive disorders in embryo transfer recipient mares in Brazil.
Authors: Pinna A, Martins G, Hamond C, Medeiros M A, de Souza G N, Lilenbaum W
Journal: The Veterinary record
Summary
# Editorial Summary: Leptospira serovars and reproductive failure in recipient mares Leptospirosis is an established cause of reproductive loss in horses, yet the relative contribution of different serovars to clinical disease remains poorly characterised. This Brazilian study examined 608 embryo transfer recipient mares across eight studs, stratifying them by reproductive history (69.2% with problems versus 10.4% in pregnant controls) and screening for antibodies to Leptospira serovars using serology and PCR of urine samples. The host-adapted Bratislava serovar dominated in affected mares (64.8% of reactive animals in the problem group), whilst the incidental Copenhageni serovar was more common in healthy pregnant controls (61.5% of the smaller reactive subset). Critically, Bratislava seroreactivity showed a statistically significant association with reproductive failure (P<0.001), particularly early embryonic death, perinatal mortality, and abortion, whereas Copenhageni did not demonstrate this relationship. These findings suggest that whilst both serovars circulate in equine populations, Bratislava poses substantially greater risk to reproductive competence—a distinction worth considering during herd health investigations and when interpreting serological results in mares with unexplained losses. Practitioners managing embryo transfer programmes should weigh leptospirosis screening and vaccination protocols accordingly, particularly in endemic regions where serovar prevalence data may vary.
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Practical Takeaways
- •Screen recipient mares for Leptospira, particularly the Bratislava serovar, as it is strongly associated with embryonic loss, perinatal death, and abortion in embryo transfer programmes
- •Seropositivity to Bratislava in mares with poor reproductive history should raise suspicion for leptospirosis-induced losses; consider urine PCR testing to confirm active infection and guide treatment decisions
- •Implement biosecurity and herd health protocols targeting Leptospira control in embryo transfer centres, as Bratislava appears to be the primary reproductive pathogen in semiextensive breeding systems in Brazil
Key Findings
- •44.9% (273/608) of mares were seroreactive to Leptospira (titre ≥200), with Bratislava predominating at 62.3% of reactive mares
- •Bratislava seroreactivity was significantly associated with reproductive problems (P<0.001) including early embryonic death, perinatal death, and abortion
- •Group A mares with reproductive problems showed 69.2% seroreactivity (247/357) predominantly against Bratislava (64.8%), versus only 10.4% reactivity in Group B pregnant mares (26/251), mostly against Copenhageni
- •55.2% (16/29) of urine samples from affected mares were PCR-positive for Leptospira species, confirming active infection