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

Abstract

Simple Summary A perineal hernia is a condition that primarily affects older intact male dogs. It occurs when the muscles that support the pelvic organs weaken or fail. As these muscles weaken, organs such as the rectum, colon, or bladder may move into the perineal region. This creates visible swelling and causes difficulty defecating or urinating. Although this condition is well known in veterinary practice, the exact changes that occur in the area’s blood vessels and nerves are not fully understood. This study examined the perineal regions of two healthy dogs and three dogs with perineal hernias; however, only one control underwent contrast enhanced fluoroscopy, and neural dissection was performed on one control and on the dog with bilateral hernia. We found that dogs with hernias showed significant differences in the position and structure of the arteries and nerves compared to healthy dogs. The changes were more severe in dogs with long-standing or bilateral hernias where the organs had moved into the hernial sac, severely damaging the supporting muscles. Understanding how anatomy changes in these cases can help veterinarians plan safer, more effective surgeries. Our findings underscore the importance of considering individual anatomical variations when treating perineal hernias in dogs. Abstract 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.