Half semitendinous muscle transposition technique to repair ventral perineal hernias in dogs

Introduction: The use of a semitendinosus muscle flap has been reported to be useful in cases of ventral perineal hernia. The purpose of the study is to present a modification of the semitendinosus muscle flap technique for the repair of ventral perineal hernias in small size dogs. Material and Methods: Medical records of dogs with lateral and ventral perineal hernia treated with a modified semitendinosus muscle flap were reviewed. The muscle was transposed to fill the pelvic defect on the opposite side. The modified technique consisted in longitudinally splitting the muscle in two parts, with the lateral half of the muscle remaining in its anatomic position. Colo- and vas deferens pexy were performed. Intact male dogs were castrated. Wound complications, limb function and outcome were assessed by physical and rectal examinations and by phone interview. Results: Four dogs were treated. Mean age and weight were 9. 2 years and 8.2 kg, respectively. The disease was unilateral and bilateral in 3 and 1 dogs, respectively. The right or left split semitendinosus muscle was transposed in 2 cases each. In 1 case the modified technique was combined to internal obturator muscle flap. Colo- and vas deferens pexy were performed in 3 dogs. The mean follow up time was 301.5 days. Wound complications and lameness were not observed; no recurrence of perineal hernia was detected. An improvement of quality of life was noted despite of persistence of intermittent tenesmus in 2 cases. Discussion: In this series muscle size represented a problem in small size dogs because of its thickness and width. To address this problem, the muscle was longitudinally divided in two parts. The results reported showed that half of the semitendinosus muscle can be safely transposed to repair ventral perineal defects. On postoperative rectal examinations a good lateral and ventral muscular rectum support was appreciated, even stronger when the semitendinosus transposition was combined on the same side to the internal obturator muscle flap. Few postoperative complications were reported and perineal hernia did not recur.