Sacral diameter

The sacral diameter is a pelvic measurement used to assess the anatomy of the pelvic area, particularly in the context of obstructive dystocia and constipation. It is determined from a laterolateral radiograph or multiplanar reconstructed CT images of the pelvis.

The sacral diameter has been defined as the vertical distance between the caudoventral extremity of sacrum and the pubic symphysis, othogonal to the pubic symphysis.

The anatomic landmarks for the sacral diameter are very similar to those for the vertical diameter in the dog. These two values are therefore very close.

The mean values reported in the literature for the sacral diameter in Scottish terrier with normal parturition (9.5 +/- 0.9 kg) and dystocia (9.8 +/- 0.8 kg) are respectively : 4.6 +/- 0.12 cm - 4.2 +/- 0.07 cm.