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The Journal of veterinary medical science2021; 83(12); 1907-1912; doi: 10.1292/jvms.21-0163

High prevalence of Mycoplasma equirhinis in Thoroughbred horses with respiratory symptoms in autumn 2018.

Abstract: Mycoplasma species are often isolated from horses with respiratory symptoms; however, the pathogenicity of Mycoplasma is still unclear. In autumn of 2018, we encountered an increase in cases with respiratory symptoms, mainly coughing, in a group of Thoroughbred racehorses in Japan. We examined tracheal wash samples obtained from 40 of those cases. Bacteria and viruses that commonly cause respiratory symptoms were investigated, and anaerobes were detected in only 5 cases and Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) was detected in only 1 case of 40 cases with loop-mediated isothermal amplification assay. S. zooepidemicus and Streptococcus pneumoniae were isolated at a bacterial count of higher than 1.0 × 10 CFU/ml from 5 and 2 cases of 28 cases cultured, respectively. None of the viruses investigated was detected in 40 cases. Mycoplasma equirhinis (M. equirhinis) was isolated from 40.0% (16/40) of the cases, which was higher than previously reported isolation rates. The rate of M. equirhinis isolation in the cases from 2018 was significantly higher than the isolation rates in the other horses: clinical cases with respiratory symptoms in 2019-2020 (13.6%, 3/22) and healthy horses (13.5%, 5/37) in Japan. In this study, the isolation rate of M. equirhinis from horse group with cough symptoms in 2018 was high and no other common etiological agents were detected. The pathogenesis of M. equirhinis is still unclear, however, M. equirhinis might have been associated with respiratory symptoms in the Thoroughbred horse cases in 2018.
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Publication Date: 2021-11-04 PubMed ID: 34732605PubMed Central: PMC8762419DOI: 10.1292/jvms.21-0163Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The study reports a high occurrence of the bacteria Mycoplasma equirhinis in racehorses experiencing respiratory symptoms during the autumn of 2018 in Japan, although the role of this bacteria in causing the symptoms remains uncertain.

Background and Objectives

  • The researchers sought to identify the cause of a surge in racehorses in Japan presenting with respiratory symptoms, primarily coughing, during the autumn of 2018.
  • Mycoplasma species are frequently found in horses with respiratory symptoms, yet its role in causing such symptoms is not fully understood.

Methodology

  • The researchers collected tracheal wash samples from 40 affected horses.
  • They tested these samples for common bacterial and viral causes of respiratory disease, including Streptococcus equi and Streptococcus pneumoniae, using a loop-mediated isothermal amplification assay and bacterial cultures.
  • The researchers also examined the samples for the presence of Mycoplasma equirhinis (M. equirhinis).
  • The researchers compared the rate of M. equirhinis isolation in these 40 horses with rates in other horses presenting with respiratory symptoms in 2019 and 2020, and with healthy horses.

Results and Interpretations

  • M. equirhinis was detected in 40% of tracheal wash samples from the autumn 2018 cohort. This figure was substantially higher than those found in other groups tested.
  • Only a small number of these 40 horses tested positive for other common bacterial pathogens; specifically, S. equi in one horse, and S. pneumoniae in two horses.
  • None of the 40 samples tested positive for any of the investigated viral pathogens.
  • While the study findings revealed a higher incidence of M. equirhinis in horses exhibiting respiratory symptoms in 2018 compared to other years and to healthy horses, the pathogenic role of M. equirhinis remains unclear.

Conclusions

  • This study found a high isolation rate of M. equirhinis in racehorse tracheal wash samples collected during an outbreak of respiratory symptoms in Japan in the autumn of 2018.
  • The findings suggest that M. equirhinis might have been linked with these symptoms; however, further research into the pathogenicity of M. equirhinis is necessary to firmly establish this potential connection.

Cite This Article

APA
Uchida-Fujii E, Kinoshita Y, Niwa H, Maeda T, Nukada T, Ueno T. (2021). High prevalence of Mycoplasma equirhinis in Thoroughbred horses with respiratory symptoms in autumn 2018. J Vet Med Sci, 83(12), 1907-1912. https://doi.org/10.1292/jvms.21-0163

Publication

The Journal of veterinary medical science
ISSN: 1347-7439
NlmUniqueID: 9105360
Country: Japan
Language: English
Volume: 83
Issue: 12
Pages: 1907-1912

Researcher Affiliations

Uchida-Fujii, Eri
  • Microbiology Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi 329-0412, Japan.
Kinoshita, Yuta
  • Microbiology Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi 329-0412, Japan.
Niwa, Hidekazu
  • Microbiology Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi 329-0412, Japan.
Maeda, Tatsuya
  • Research Planning and Coordination Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi 329-0412, Japan.
Nukada, Toshio
  • Racehorse Clinic, Ritto Training Center, Japan Racing Association, Ritto, Shiga 520-3085, Japan.
Ueno, Takanori
  • Microbiology Division, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi 329-0412, Japan.

MeSH Terms

  • Animals
  • Horse Diseases / epidemiology
  • Horses
  • Mycoplasma
  • Prevalence
  • Streptococcal Infections / epidemiology
  • Streptococcal Infections / veterinary
  • Streptococcus equi

Conflict of Interest Statement

The authors have nothing to disclose.

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Citations

This article has been cited 4 times.
  1. Dawood A, Algharib SA, Zhao G, Zhu T, Qi M, Delai K, Hao Z, Marawan MA, Shirani I, Guo A. Mycoplasmas as Host Pantropic and Specific Pathogens: Clinical Implications, Gene Transfer, Virulence Factors, and Future Perspectives. Front Cell Infect Microbiol 2022;12:855731.
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  2. 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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  3. Martineau M, Ambroset C, Lefebvre S, Kokabi É, Léon A, Tardy F. Unravelling the main genomic features of Mycoplasma equirhinis. BMC Genomics 2024 Sep 20;25(1):886.
    doi: 10.1186/s12864-024-10789-ypubmed: 39304803google scholar: lookup
  4. Kinoshita Y, Niwa H, Uchida-Fujii E, Ueno T. A real-time PCR assay for the quantification of Mycoplasma equirhinis in tracheal wash samples from Thoroughbred horses. J Vet Diagn Invest 2024 Jan;36(1):108-111.
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