Effect of intrauterine application of ozone on neutrophil migration and subclinical endometritis in dairy cattle

Abstract

The objective was to determine whether an ozonized saline solution (O3SS) increases endometrial polymorphonuclear neutrophils (PMNN) (Exp 1) and to challenge the preventive effect of O3SS on subclinical endometritis (SCE) (Exp 2). In Exp 1, 38 primiparous Holstein cows were used. Cows with (WHM) and no history of postpartum metritis (NHM) were included; they were then divided into control (CTRL, saline solution) or O3SS (6.7 ± 0.3 ppm) subgroups. At 55 d postpartum, 50 ml of CTRL or O3SS was applied intrauterinely and at 48 h, the quantity of PMNN was recorded by endometrial cytology. In Exp 2, 26 primiparous NHM Holstein cows were used. The cows were randomly distributed in CTRL or O3SS. Two doses of 50 ml were administered with an interval of 7 d (first application 11.3 ± 0.4 d postpartum). At d 30 postpartum, SCE (≥6 % PMNN) was diagnosed. WHM cows had higher numbers of endometrial PMNN compared to NHM cows (13.9 ± 6.2 vs 1.0 ± 0.46, P<0.05). The WHM-CTRL group had a higher number of PMNN than NHM-CTRL (17.0 ± 9.6 vs 0.1 ± 0.1, P<0.05), while the WHM-O3SS and NHM-O3SS groups (10.4 ± 8.1 vs 1.8 ± 4.8, P>0.05) and the NHM-CTRL and NHM-O3SS groups (0.1 ± 0.1 and 1.8 ± 4.8, P>0.05) were not different. A statistical trend (P=0.09) of lower percentage of SCE was observed in the CTRL group compared to O3SS (15.4 and 46.2 %, respectively). In conclusion, transcervical O3SS does not increase the number of endometrial PMNN and preventive treatment with O3SS applied to NHM cows did not decrease SCE. The results suggest a possible anti-inflammatory effect of the ionized saline solution treatment.