Placental abnormalities associated with Leptospira interrogans infection in naturally infected mares.
Authors: Aymée L, Dantas F T D R, Ezepha C, Motta D, Carvalho-Costa F A, Di Azevedo M I N, Lilenbaum W
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Reproductive leptospirosis in mares remains underrecognised despite causing significant economic loss through abortion, placental disease, stillbirths and weak foal syndrome. This field-based investigation examined a naturally infected herd experiencing elevated rates of placentitis and pregnancy loss, collecting serum and cervicovaginal mucus samples from ten pregnant mares (eight with ultrasonographic placental abnormalities) for serological and molecular analysis. Polymerase chain reaction targeting the lipL32 gene detected *Leptospira interrogans* in cervicovaginal secretions from 50% of mares tested, with subsequent gene sequencing confirming the pathogenic serovar; notably, infected mares showed no obvious clinical signs, demonstrating the silent, subclinical nature of equine genital leptospirosis. These findings provide field evidence that *L. interrogans* colonisation is associated with placental pathology in naturally infected mares, supporting the need for routine leptospirosis screening as part of comprehensive reproductive health protocols, particularly in herds with unexplained pregnancy complications. Inclusion of cervicovaginal sampling and PCR-based diagnostics in reproductive examinations may help equine practitioners identify subclinical infections before they manifest as substantial breeding losses.
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Practical Takeaways
- •Include leptospirosis testing (PCR of cervicovaginal mucus) in reproductive management protocols for mares with placentitis, abortion, or weak foals, as infection may be subclinical
- •Recognize that equine genital leptospirosis is a chronic silent syndrome; ultrasound detection of placental abnormalities warrants leptospirosis investigation
- •Implement herd-level screening when multiple cases of placentitis or abortions occur, as this may indicate L. interrogans circulation in the population
Key Findings
- •50% (5/10) of mares with placental abnormalities on ultrasonography were positive for Leptospira interrogans in cervicovaginal mucus by lipL32-PCR
- •All PCR-positive samples were confirmed as Leptospira interrogans through secY gene sequencing
- •Placental abnormalities were present in mares with reproductive subclinical leptospirosis syndrome
- •High herd occurrence of placentitis and abortions was associated with L. interrogans infection