Leptospiral Abortion: An Update

Infection of the pregnant mare by pathogenic leptospires can result in abortion, stillbirth, or birth of a weak foal. Yearly assessments of leptospiral abortions is important, as disease incidence can vary based on fluctuating environmental factors and population densities. This excerpt provides a brief update of leptospiral abortions diagnosed during the 2010 foaling season (July 1, 2010 - Feb. 1, 2011). For reporting purposes, a foaling season is 365 days after July 1. For example, the 2010 foaling season was July 1, 2009 - June 30, 2010.

Thirty-one cases of equine leptospiral abortion have been diagnosed at the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) since the last update in the October 2009 issue of Equine Disease Quarterly. All 31 cases were diagnosed during the 2010 foaling season, and no cases have been diagnosed through Feb. 1 of the 2011 foaling season. Newly reported abortions occurred from September 2009 to March 2010, and affected fetuses ranged from five to 10.5 months of gestation. The abortions were primarily sporadic, as a single leptospiral abortion was diagnosed on 20 farms, four farms had two leptospiral abortions, and three leptospiral abortions occurred on one farm.

Identification of an infected mare is challenging because most do not exhibit premonitory signs prior to abortion. Novel molecular assays, such as polymerase chain reaction (PCR), have added in the diagnosis of leptospiroses. Analysis with PCR can identify the acute blood phase of infection (leptospiremia) and chronic renal (kidney) infection of horses that shed leptospires in their urine. Mares that have PCR-positive urine samples should be appropriately managed to reduce exposure of this zoonotic pathogen to people, pregnant mares, and the environment.

The UKVDL offers a PRC assay for the identification of pathogenic Leptospira sp. in urine and tissue samples.

CONTACT: Dr. Alan Loynachan, 859/257-8283, alan.loynachan@uky.edu, Veterinary Diagnostic Laboratory, University of Kentucky, Lexington, Kentucky

This is an excerpt from Equine Disease Quarterly, funded by underwriters at Lloyd's, London, brokers, and their Kentucky agents.

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Equine Disease Quarterly

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