| This thesis is an investigation of the diagnosis and treatment of postpartum subclinical endometritis in dairy cows. A randomized clinical trial was conducted in two commercial dairy herds in south-western Ontario. Cows were examined at visit 1 (V1), 20--33 days in milk (DIM), for the presence of abnormal vaginal discharge externally on the tail, perineum and vulva, and by vaginoscopy. Clinically normal cows (n = 230), based on the absence of abnormal vaginal discharge, were selected. The reproductive tract of selected cows was examined by uterine palpation per-rectum, ultrasonography and endometrial cytology evaluation using the cytobrush. All cows included in the study were re-examined at visit 2 (V2) 14 days after V1. Survival analysis was used to determine a case definition of subclinical endometritis based on factors associated with risk of pregnancy. Based on reproductive performance, the presence of >18% polymorphonuclear (PMN) cells and fluid in the uterus (FIU) were the criteria to identify cows with subclinical endometritis at V1. The prevalence of subclinical endometritis at V1 was 18.0%. Diagnostic criteria based on uterine palpation per-rectum had no association with the risk of pregnancy. The presence of >10%PMN and FIU were the criteria to identify cows with subclinical endometritis at V2. The prevalence of subclinical endometritis at V2 was 15.8%. Cows with subclinical endometritis at both V1 and V2 had a 60% reduced risk of pregnancy (p < 0.01). Cows with >18%PMN or FIU alone and either >18%PMN or FIU had a decreased reproductive performance (p > 0.01).; Cows were randomly assigned at V1 to one of three treatment groups, a single intramuscular injection of 500 mug of cloprostenol (CLO), a single intrauterine infusion of 500 mg of benzathine cephapirin (CEP) and untreated control (CON). Among cows with >18%PMN, CEP treatment significantly improved the reproductive performance (p = 0.03). Among all cows, and among cows with PEC (or) FIU, both CLO and CEP treatments significantly increased the risk of pregnancy (p > 0.01). Among cows with subclinical endometritis (PEC+FIU), there was no significant difference in reproductive performance among treatments at V1. |
