Fungal endometritis in broodmares: clinical presentation, prevalence in Ireland and diagnostic performance of cytology

BACKGROUND: Fungal endometritis is an uncommon uterine condition associated with poor fertility. AIMS/OBJECTIVES: This study aimed to 1) provide a descriptive summary of 11 cases of fungal endometritis, 2) assess prevalence trends of fungal endometritis over time, 3) assess fungal species distribution in diagnostic samples, and 4) evaluate the diagnostic accuracy of cytology. METHODS: Study 1 reviewed records of 11 mares diagnosed with fungal endometritis for history, presentation, treatment, and outcome. Study 2 analysed 6,727 uterine samples (swabs and lavages; 2019-2024) for factors influencing fungal culture positivity and species distribution. Additionally, 418 uterine lavages with cytology and negative bacterial culture were used to test the diagnostic accuracy of polymorphonuclear neutrophils (PMNs) and fungal elements (FE) for culture outcome. RESULTS: In Study 1, all mares had prior antimicrobial use and reproductive tract defects. History of abortion or traumatic peripartum events (8/9) and intrauterine chemical curettage (9/10) were frequent. Fertility prognosis was acceptable (6/9 pregnancies within 12 months) but management was often prolonged and included surgery (e.g. uteropexy). In Study 2, fungal culture positivity depended on both sampling method and culture conditions (uterine lavage: 7%; swab with fungal culture: 19%, and without: 1%; p < 0.01). Prevalence increased significantly over time (adjusted OR 1.1, 95% CI 1.0-1.4). Isolates included yeasts (52.7%), and moulds (47.3%). Cytology showed high specificity: PMNs (91.3%, 95% CI 88.0 - 94.0%) and FE (99.7%, 95% CI 98.5 - 100%). CONCLUSION: Established and potentially emerging risk factors were described. Fungal endometritis prevalence increased during the period of the study. Uterine lavage cytology can aid diagnosis in case of negative bacterial growth.