Screening for Taylorella equigenitalis in Equine Semen: An Exploratory Study

Area of Science:

• Veterinary Microbiology
• Equine Reproduction
• Molecular Diagnostics

Background:

• Taylorella equigenitalis (CEMO) causes Contagious Equine Metritis, a significant reproductive disease in horses.
• Accurate and sensitive detection of CEMO in equine semen is crucial for disease control and prevention of transmission.
• Current diagnostic methods for CEMO screening in semen have limitations that require further investigation.

Purpose of the Study:

• To compare the diagnostic sensitivity of bacterial culture and quantitative PCR (qPCR) for detecting CEMO in equine semen.
• To evaluate the impact of semen extenders and storage time on the performance of both diagnostic methods.
• To determine the reliability of PCR for screening equine semen for CEMO, considering its detection limits.

Main Methods:

• Equine semen samples (raw and extended) from two stallions were collected and stored.
• Samples were artificially inoculated with known concentrations of CEMO at different time points (7 and 23 days post-ejaculation).
• Serial dilutions were prepared and subjected to both bacterial culture and quantitative PCR analysis.

Main Results:

• Bacterial culture detected CEMO in raw semen effectively but showed significantly reduced sensitivity in extended semen.
• PCR sensitivity was unaffected by semen extenders, demonstrating consistent performance across sample types.
• PCR detection limits were estimated between 10^4 and 10^5 cfu/mL, aligning with reported natural infection levels.

Conclusions:

• Quantitative PCR offers a more reliable method for screening equine semen for CEMO compared to culture, especially when semen extenders are used.
• PCR's robustness against sample preparation variations makes it a valuable tool for routine diagnostics in equine breeding programs.
• Further research into natural CEMO concentrations in infected stallions' semen is warranted to fully contextualize diagnostic findings.