Holstein (65%), Polled Hereford (25%), and Aberdeen Angus (10%). Their ages ranged between 2 and 8 months; 42.4% were males and 57.6% were females. All calves belonged to farms located in the northeastern region of Buenos Aires Province, Argentina. On all farms, data on sex, weight, and assistance type were recorded at calving.

The obstetric assistance of dystocia in field conditions promotes greater bacterial contamination of the uterus, causing subclinical endometritis. The aim of this study was to determine the occurrence of subclinical endometritis in beef heifers receiving professional calving assistance, and to evaluate endometrial cytology as a diagnostic technique compared to uterine biopsy. A group of 829 Angus heifers were assisted at calving. Dystocia was classified based on difficulty at assistance, which was estimated as complex or simple. At the end of the calving season, 93 dystocic heifers were reported (10.7%). The percentage of simple resolution and complex resolution was 88.2% and 11.8%, respectively. After 60 days of calving, all animals underwent a gynecological examination, endometrial cytology, and uterine biopsy. In all, 38.9% of heifers presented subclinical endometritis diagnosed by endometrial cytology (sensitivity = 78.6%, specificity = 95.8%). There was a significant association (r = 0.8528) between uterine cytology and uterine biopsy. No associations were observed between endometrial cytology or biopsy and calf viability, or between endometrial cytology or biopsy and calving resolution. Endometrial cytology is a noninvasive technique with high specificity and repeatability for the diagnosis of subclinical endometritis postpartum in dystocic beef heifers.