The responsiveness of subclinical endometritis to a nonsteroidal antiinflammatory drug in pasture-grazed dairy cows.

The objective of this study was to determine if the inflammation associated with subclinical endometritis (SCE) is a part of the mechanism by which reproductive performance is reduced in cows with this disease. If it is, reducing inflammation associated with SCE with a nonsteroidal antiinflammatory drug (NSAID) should reduce the severity [as measured by average polymorphonuclear cell (PMN) percentage] of uterine pathology and improve reproductive performance. It was also investigated whether the NSAID treatment reduced metabolic indicators of systemic inflammation previously reported to be altered in cows with SCE. Holstein-Friesian and Friesian-Jersey cross dairy cows (n=213) were paired by calving date and d-14 uterine PMN percentage and randomly assigned to 3 injections at intervals of 3 d of an NSAID (1.4 mg of carprofen/kg; n=104) between 21 and 31 d postpartum or left as untreated controls (n=109). Cows with ≥14% PMN (upper quartile of PMN percentage) in the cytological sample collected at d 14 postpartum were defined as having SCE. The average d-14 PMN percentage was low (9.9%) and a high self-cure rate of SCE (>90%) at d 42 was observed. Treatment with an NSAID reduced plasma concentrations of aspartate aminotransferase and increased pregnancy rate in SCE cows. However, no effect of the NSAID treatment was observed on PMN percentage at d 42, postpartum anovulatory interval, or milk production. Compared with cows without SCE, cows with SCE had lower plasma albumin concentration, albumin:globulin ratio, and body condition score, but higher nonesterified fatty acids on the day of calving. These results indicate that cows with SCE are experiencing a physiological dysfunction, including lower body condition, liver dysfunction, and greater metabolic challenge during the periparturient period. Further research is required to determine the effect of NSAID on SCE and to evaluate the influence of timing of drug application on treatment effectiveness.