Application of computed tomography for the evaluation of obstetrically relevant pelvic parameters in German Holstein-Friesian cows

The aim of this study was to use computed tomography for the evaluation of the suitability of external pelvimetry to determine obstetrically relevant parameters. External pelvimetric measurements obtained in vivo using calipers and internal pelvimetric measurements obtained in vitro using computed tomography were taken in 30 German Holstein-Friesian cows (Bos taurus). All measurements were highly reproducible with intraclass correlation coefficients ≥98%. Hip width was the external variable with the highest correlation to internal variables, particularly pelvic inlet area and circumference, pelvic volume, medial horizontal diameter of the pelvic inlet, and the narrowest horizontal diameter of the midpelvis (r2 > 0.60, P<0.0001). The pelvic inlet area and circumference, the pelvic volume, and the diagonal diameter of the pelvis were sufficiently predicted with the aid of external pelvic measurements and age (r2≥0.80, P<0.0001). The results of this study show that external pelvimetry yields reliable information about the size of the pelvis when the age of the cow is considered.