Preliminary Anatomical and Imaging Characterization of Vascular and Neural Changes in Dogs with Perineal Hernia.

A perineal hernia in dogs results from a failure of the pelvic diaphragm and is often accompanied by a displacement of the pelvic and abdominal organs. However, detailed descriptions of accompanying vascular and neural alterations are limited. This study uses a combination of fluoroscopic imaging and anatomical dissection to characterize the perineal arterial and neural anatomy in two control dogs and three dogs with unilateral or bilateral perineal hernias; however, only one control underwent fluoroscopy, and neural dissection was performed on one control and on the bilateral case. In the control specimen, the vascular pattern followed the classical NAV arrangement. In contrast, the hernia cases exhibited marked variability, including altered origins and lengths of the dorsal and ventral perineal arteries; long- or short-type internal iliac and internal pudendal arteries; and displacement or deterioration of the superficial perineal nerve. These changes were most pronounced in the dog with a bilateral hernia, which was accompanied by severe degeneration of the levator ani and coccygeus muscles and herniation of the colon, urinary bladder, and urethra. Fluoroscopic findings closely corresponded with anatomical observations, demonstrating the value of imaging in the preoperative assessment of vascular variations. Overall, this study provides a comprehensive description of the neurovascular and muscular modifications associated with perineal hernias and emphasizes the need for individualized anatomical evaluations to optimize surgical planning and reduce intraoperative risks.