An investigation of a recent outbreak of nocardioform placentitis caused abortions in horses.
Abstract: Nocardioform placentitis associated with gram positive branching actinomycetes caused a record number of abortions in mares diagnosed by the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) affecting the 2011 foal crop (2011 foal crop: the cohort of foals conceived during the 2010 breeding season). The goal of the present study is to make a comprehensive analysis of this outbreak in terms of frequencies of the bacteria causing nocardioform placentitis mediated abortions and to investigate the ages of fetuses, abortion months and breeding times. In the present study, characteristic slow-growing, pungent/soil odor gram positive branching actinomycetes were recovered in high numbers in placental specimens in 76 abortion cases diagnosed as nocardioform placentitis by pathologists. To determine the type of actinomycetes responsible for the abortions, PCR assays were performed on the gram positive branching bacilli. The most prominent actinomycetes species were Amycolatopsis spp. (37 cases, 48.7%) and Crossiella equi (C. equi) (22 cases, 28.9%). Six cases (7.9%) contained both Amycolatopsis spp., and C. equi. 10 isolates were unidentified by PCR assays and shown to have high DNA sequence homology to Streptomyces species, Microbacterium species, Nocardia species and Allokutzneria species, as evidenced by 16 rRNA gene sequencing and phylogenetic analysis. Nocardioform placentitis related abortions occurred mostly between December 2010 and April 2011 happening exclusively in the last trimester. Breeding time of aborted pregnancies ranged from March 2010 to July 2010, suggesting that if transmission of the actinomycetes agents occurred during breeding, it was not related to a specific season.
Published by Elsevier B.V.
Publication Date: 2012-02-21 PubMed ID: 22410309DOI: 10.1016/j.vetmic.2012.02.023Google Scholar: Lookup
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Summary
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This research investigated an outbreak of pregnancy terminations in female horses caused by a bacterial infection known as nocardioform placentitis, with results identifying specific species of bacteria involved and the timing of these incidents in relation to breeding seasons.
About the Research
- During the 2011 foaling season, researchers at the University of Kentucky Veterinary Diagnostic Laboratory noticed an unusually high incidence of pregnancy losses in mares associated with nocardioform placentitis.
- The study aimed to analyze the outbreak in detail, focusing on identifying the types of bacteria causing this condition, the age of the affected fetuses, the time during breeding when the abortions occurred, and the specific months that saw the highest number of cases.
Nocardioform Placentitis
- In 76 cases, the placental specimens showed high volumes of slow-growing, gram-positive branching actinomycetes, which are bacteria found in soil that were identified as the cause of nocardioform placentitis in these horses.
- To identify the specific type of actinomycetes related to the condition, PCR assays, a common technique for amplifying and identifying DNA, were used.
- The majority of bacteria identified were Amycolatopsis spp. (48.7% of cases) and Crossiella equi (28.9% of cases). Some specimens (7.9%) had both bacteria present.
Unidentified Bacterial Isolates
- There were also 10 isolates that could not be identified using the PCR technique. However, further 16S rRNA gene sequencing and phylogenetic analysis suggested that these isolates showed high DNA sequence similarity with certain Streptomyces species, Microbacterium species, Nocardia species, and Allokutzneria species.
Timing of Incidents
- The study found that abortions related to nocardioform placentitis primarily occurred between December 2010 and April 2011, exclusively during the last trimester of gestation.
- The study also found that the conception time of the aborted pregnancies ranged from March 2010 to July 2010, thus suggesting transmission of the causative agent may occur during breeding, although it did not appear to be associated with a specific season.
Importance of Findings
- The findings from this research provide valuable information in understanding the bacterial agents involved in causing nocardioform placentitis in mares and moreover, the timing of these potentially catastrophic incidents.
- The results could help inform prevention and control strategies in horse breeding and improve pregnancy outcomes in the industry.
Cite This Article
APA
Erol E, Sells SF, Williams NM, Kennedy L, Locke SJ, Labeda DP, Donahue JM, Carter CN.
(2012).
An investigation of a recent outbreak of nocardioform placentitis caused abortions in horses.
Vet Microbiol, 158(3-4), 425-430.
https://doi.org/10.1016/j.vetmic.2012.02.023 Publication
Researcher Affiliations
- Veterinary Diagnostic Laboratory, College of Agriculture and Public Health, University of Kentucky, Lexington, KY 40512-4125, USA. erdal.erol@uky.edu
MeSH Terms
- Abortion, Veterinary / epidemiology
- Abortion, Veterinary / microbiology
- Actinomycetales / genetics
- Actinomycetales / isolation & purification
- Actinomycetales Infections / microbiology
- Actinomycetales Infections / veterinary
- Animals
- Bacteria / genetics
- Bacteria / isolation & purification
- Disease Outbreaks / veterinary
- Female
- Horse Diseases / epidemiology
- Horse Diseases / microbiology
- Horses
- Kentucky / epidemiology
- Phylogeny
- Placenta / microbiology
- Placenta Diseases / epidemiology
- Placenta Diseases / microbiology
- Pregnancy
- RNA, Ribosomal, 16S / genetics
Citations
This article has been cited 6 times.- Li L, Maboni G, Lack A, Gomez DE. Nontuberculous Mycobacteria in Horses: A Narrative Review. Vet Sci 2023 Jul 6;10(7).
- Ricard RM, St-Jean G, Duizer G, Atwal H, Wobeser BK. A 13-year retrospective study of equine abortions in Canada. Can Vet J 2022 Jul;63(7):715-721.
- El-Sheikh Ali H, Loux SC, Kennedy L, Scoggin KE, Dini P, Fedorka CE, Kalbfleisch TS, Esteller-Vico A, Horohov DW, Erol E, Carter CN, Smith JL, Ball BA. Transcriptomic analysis of equine chorioallantois reveals immune networks and molecular mechanisms involved in nocardioform placentitis. Vet Res 2021 Jul 8;52(1):103.
- Carter CN, Smith JL. A proposal to leverage high-quality veterinary diagnostic laboratory large data streams for animal health, public health, and One Health. J Vet Diagn Invest 2021 May;33(3):399-409.
- van Heule M, Verstraete M, Norris JK, Graniczkowsa KB, Scoggin KE, Ali HE, Ball BA, De Spiegelaere W, Daels P, Weimer BC, Dini P. Beyond nocardioform: Transcriptionally active microbes and host responses in equine mucoid placentitis. Equine Vet J 2026 Mar;58(2):601-618.
- Hardefeldt L, Thomas K, Page S, Norris J, Browning G, El Hage C, Stewart A, Gilkerson J, Muscatello G, Verwilghen D, van Galen G, Bauquier J, Cuming R, Reynolds B, Whittaker C, Wilkes E, Clulow J, Burden C, Begg L. Antimicrobial prescribing guidelines for horses in Australia. Aust Vet J 2025 Dec;103(12):781-889.
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