A hernia is apparent when the contents of the swelling can be pushed back into the pelvic cavity. This may be facilitated by elevating the animal's hindlimbs. Simultaneous palpation of the perineal enlargement and rectal examination aids in determining whether there is continuity between the swelling and peritoneal cavity, Digital examination of the rectum often reveals a lateral deviation or diverticulum into the hernial area. This deviation results in accumulation of feces in the return, and causes the animal to strain. During the course of the examination, the feces can be removed from the diverticulum, It then will be possible to pass the finger into it and observe its movement under the skin, Affected patients may only display the usual signs of discomfort, but if the bladder becomes strangulated and distended with urine following herniation, the swelling may be greatly enlarged and the overlying skin may be tense, blue-red, and exude serum. It may or may not be possible to catheterize the bladder in this case. The diagnosis of bilateral hernia sometimes is difficult because its reduction is not easy. A large unilateral hernia may migrate ventral to the anus into the opposite side and appear to be bilateral.
TreatmentMost cases of perineal hernia are not emergency cases. However, those with acute complications, such as retroflexion of the bladder and inability to urinate, must be treated as emergencies.
Relief can often be obtained by passing a catheter into the bladder. if this is not possible, wine can be removed by performing paracentesis. A 20 gauge needle or smaller is adequate. Once the bladder is emptied, an attempt can be made to reduce the hernia. When the hernial contents have been reduced, the animal should be given a narcotic to minimize straining. Such patients are suitable candidates for surgery in 24 hours. Once the diagnosis has been established surgery should not be delayed. if surgery is delayed the patient should be fed a low-residue diet for 48 hours prior to surgery. The feces are then soft in consistency and the danger of post-operative wound disruption is reduced, Recurrence of perineal hernia is not common and has been reported to recur in two to forty percent of the cases.
Repair of Perineal Hernia
The hernial funnel extends from the pelvic cavity to the hernial sac lateral to the anus. The hernia is limited ventrally and laterally by the walls of the pelvis and medially by the rectum.
The levator ani is a thin fan-shaped muscle that arises from the pelvic surface of the ischium and pubis at the pelvis symphysis, the cranial border of the pubis and the pelvic surface of the shaft of the ilium. Iris inserted on the external anal sphincter and caudal vertebrae. The two muscles together with their fascial layers form the pelvic diaphragm through which the genitourinary and digestive tracts open to the outside, When these muscles separate, relax, or become atrophic, the abdominal or pelvic organs may push through the defect. The hernia occurs between the external anal sphincter and the levator ani muscles. if the perineal fascia which surrounds the anus and is confluent with the gluteal fascia stretches or ruptures, the hernial contents prolapse lateral to the anus and are confined only by the skin.
Surgical Technique for Perineal Hernia Repair
A purse-string suture is placed around the anus to prevent defecation during the operation. It is best to place the patient on its sternum and elevate the hindquarters. The tail is pulled forward and laterally to expose the perineal region. The operation is designed to reconstruct the pelvic diaphragm. Complete reconstruction may not be possible due to tearing or atrophy of muscle; closure of the hernial funnel and obliteration of space may be all that can be accomplished.
A half circle skin incision is made over the hernia and extended an adequate distance above and below the hernia to facilitate manipulation of the tissues. Frequently there will be no evidence of fascia and fibrous tissue, and the muscles will be atrophied and intermingled with omentum-like, necrotic, fatty tissue, The tissue strands must be disrupted between muscle layers and the fatty tissue ligated and removed as necessary. The area is likely to be hemorrhagic and blood serum escapes when the hernial sac is entered.