Radiographic pelvimetry for assessment of dystocia in bitches: a clinical study in two terrier breeds

Radiographic pelvimetry was used to assess the role of pelvic anatomy in ob structive dystocia in bitches. Based on the history of previous whelpings, 20 Boston terrier and 14 Scottish terrier bitches were divided into two equ al groups: normally whelping bitches and bitches with obstructive dystocia. Additional whelpings during the period of study were closely observed and the pups were immediately weighed and measured. The bitches were clinically examined and the pelvis was radiographed in ventrodorsal and lateral proje ctions. Measurements from the radiographs showed a significantly smaller pe lvic size in the bitches with obstructive dystocia compared to the normally whelping bitches. Fetal-pelvic disproportion in the Scottish terrier was m ainly due to a dorsoventrally flattened pelvic canal, whereas in the Boston terrier it arose from the combination of a dorsoventrally flattened pelvic canal and big fetuses with large heads. These results suggest that radiogr aphic pelvimetry could be used to predict a disposition for dystocia in ind ividual bitches, and as a basis for selection of breeding animals.