Aim: The objective of this study was to investigate the effect of N-acetylcysteine (NAC) on the treatment of the clinical endometritis and pregnancy rate in dairy cows.

Materials and Methods: This study was performed on 36 cows with clinical signs of endometritis after VWP (voluntary waiting period, 50-60 days) on a commercial dairy farm. The clinical endometritis was diagnosed by evaluation of uterine discharge detected in the vagina. Cervical swab samples were collected to determine microorganism and the most effective antibacterial agent for the treatment. Cows were randomly allocated to NAC treatment (NAC-T) and non-NAC treatment (nNAC-T) groups. The NAC-T group (n=18) received an intrauterine infusion of amoxicillin trihydrate+potassium clavulanate (3500 mg+875 mg) in 100 mL dosages after 12 hours of an intrauterine infusion of 2% NAC during three days. Saline (total volume 100 mL) to the nNAC-T group (n=18) was given instead of NAC in the same protocol of the NAC-T group. The clinical cure rate was described as the percentage of cows with no signs of clinical endometritis (the clear or translucent mucus at vaginal examination), at the examination in first natural estrus following treatment. Animals were artificially inseminated following the first natural estrus after treatment.

Results: The clinical cure (83.3%) and pregnancy rates (66.7%) in the NAC-T group were significantly higher than those (55.5% and 27.8%, respectively) of nNAC-T group (P<0.05).

Conclusions: The usage of NAC for the treatment of the clinical endometritis in cows may increase the success of therapy and the improvement of pregnancy rate.