Effectiveness of Ozone Therapy in The Treatment of Endometritis in Mares

Endometritis is defined as inflammation of the endometrium that may be acute or chronic, infectious, or non-infectious. Endometritis is an important cause of subfertility in mares. Considering the antimicrobial characteristics, immune-stimulating ability, and low cost of ozone (O₃) therapy, we aimed to evaluate the effectiveness of intrauterine O₃ therapy as an alternative treatment for endometritis in mares. Twenty-five mares with a known reproductive history of uterine infection and inflammation were allocated into three groups: Group 1 (control; n = 7), uterine lavage with Ringer's lactate solution; Group 2 (O₃-gas; n = 9), uterine lavage with Ringer's lactate solution followed by uterine insufflation with O₂-O₃ gas mixture containing 40 µg O₃ mL^-1 for 10 minute; and Group 3 (O₃-oil; n = 9), uterine infusion of ozonized sunflower oil. Uterine inflammation was evaluated through a uterine cytological examination (cytobrush) and uterine culture (swab) for microbiological content before and after all treatments. In assessments of uterine cytology, the average number of neutrophils/field changed from 9.14 ± 3.02 to 7.71 ± 3.59 in the control group, from 10.67 ± 3.84 to 2.89 ± 3.59 in the O₃-gas group, and from 6.44 ± 2.79 to 6.55 ± 7.18 in the O₃-oil group post-treatment. The pre- and post-treatment findings in the mares treated with ozonized gas were significantly different (P < .05), unlike the findings for the mares in the control and O₃-oil groups. All mares (25/25) showed a positive uterine culture before treatment. After treatment, the percentage of mares showing positive culture results was 57%, 11%, and 22% in the control, O₃-gas, and O₃-oil groups, respectively. Our results showed the effectiveness of two groups (O₂-O₃ gas mixture and ozonized sunflower oil) for the treatment of uterine infections in mares. Thus, direct intrauterine O₃ gas infusion has been shown to be effective in treating endometritis in mares, reducing both inflammation and uterine infection.