Clinical, bacteriologic, serologic, and pathologic features of infections with atypical Taylorella equigenitalis in mares.

The research article presents a study examining the clinical, bacteriological, serological, and pathological responses of mares to atypical Taylorella equigenitalis, a bacteria often associated with equine infertility. The researchers found that these atypical strains could cause persistent infection and provoke immune responses similar to typical strains, suggesting they should be considered in diagnoses of equine infertility.

Research Methods

• The study was a prospective in vivo experiment involving 10 healthy mares.
• The mares, all in estrus, were divided into groups and inoculated via intrauterine infusion with either two isolates of the typical bacteria Taylorella equigenitalis, two isolates of atypical Taylorella, or were sham-inoculated as a control group.
• The researchers evaluated the mares’ bacteriological, serological, clinical, uterine, cytological, and pathological endometrial responses at intervals up to 111 days post-inoculation.

Results

• One atypical isolate did not cause any infection, while the second atypical isolate and the classic T equigenitalis isolates resulted in similar instances of transient metritis and cervicitis.
• Both the classic isolates and the one viable atypical isolate prompted an immune response indicated by the presence of anti-T equigenitalis complement-fixing antibodies detectable at day 11.
• The inoculated mares experienced intense neutrophilic endometritis followed by a resolving, subacute, neutrophilic-mononuclear endometrial response.
• The atypical and classic bacteria strains were found persisting in various parts of the horses’ reproductive tracts up to 111 days after inoculation.

Conclusion

• The researchers concluded that atypical Taylorella equigenitalis infections should be considered in the differential diagnoses of equine infertility, including in mares not exposed to stallions from countries where contagious equine metritis is common.
• The exact origins and prevalence of atypical Taylorella infections in US horses and donkeys are still uncertain and warrant further investigation.