Use of computed tomography to evaluate pelvic canal in cats

The objective of this study was to establish an evaluation technique for the feline pelvic cavity using computed tomography (CT). Client-owned cats with a normal pelvis (n = 50) or pelvic stenosis (n = 3) were included. We categorized pelvic CT images in the normal pelvis group into two types according to pelvic cavity shape, then calculated the sacral index (SI), pelvic canal area (PCA), and PCA/sacral width index (PSI). The reference intervals of these variables were determined based on the results in the normal pelvis group. In the normal pelvis group, the PSI, unlike the SI and PCA, was not affected by body weight. In addition to high intraobserver and interobserver reproducibilities, the PSI showed no significant differences according to pelvic cavity shape. However, the SI exhibited significant differences among pelvic cavity shapes. In the stenosis group, the postoperative PSI in all cats was within the reference interval. However, the postoperative SI in one case was lower than the reference interval. The PSI may become a new method for evaluation of the pelvic cavity, including the pelvic floor.