Effect of Intra-Uterine Infusion of Diluted N-Acetylcysteine on Equine Endometrium

1. Introduction
Previous work has shown that mares with delayed clearance or chronic endometritis produce more mucus than reproductively healthy mares. Therefore, treatment with a mucolytic agent such as N-acetylcysteine (NAC) may assist in the clearance of mucus as well as antibiotic penetration, and this combination may increase pregnancy rates.

2. Materials and Methods
Twenty-two mares were divided into 3 groups: fertile control (n = 6), fertile treatment (n = 6), and barren treatment (n = 10). Endometrial biopsies were taken before (day 1) and after (day 4) a uterine infusion of 150 ml of saline (control mares) or a 3.3% solution of NAC (30 ml of a 20% solution in 150 ml of saline; treatment mares). On days 2 and 3, the uterus was irrigated with 1 l of Lactated Ringers solution. Endometrial tissues were given a Kenney grade, and mucus production was measured by computerized image analysis. Additionally, 20 Thoroughbred mares repeatedly bred in 2008 were mated naturally after they received a 0.6% solution of NAC either one treatment cycle before breeding (n = 10) or 48 h before breeding (n = 10). Post-breeding treatments (including uterine lavage, antibiotic infusion, acupuncture, and other therapies) were performed in some mares. [...]