Introduction

Perineal hernia (PH) is defined as a defect in the pelvic diaphragm that results in an inability of the pelvic diaphragm to keep the pelvic organs in their normal position. The pelvic diaphragm is made up of levator ani muscle, coccygeus muscle, external anal sphincter muscle and perineal fascia. Muscle atrophy results in herniation of the pelvic structures occurring most frequently between the levator ani and external anal sphincter muscle. PH is bilateral in 20 to 50% of cases. Herniated abdominal contents include rectum, colon, bladder, prostate, periprostatic fat, bowel loops.

The disease primarily affects older animals, usually between 7 and 9 years old. Intact male dogs are over-represented. There is 2 to 2.7 more risks of recurrence in intact males compared to neutered ones.

The underlying cause for weakening or failure of the pelvic diaphragm is unclear. Many theories have been proposed regarding the pathogenesis of PH including:

 Hormonal imbalance: the strong predisposition of intact males suggests imbalance between oestrogens and androgens or excess of androgens. Significant differences in testosterone or oestradiol 17-B serum concentrations between dogs with PH and non-affected dogs have not been demonstrated.

 Both mechanical and hormonal influence in dogs with prostatic disease.

 Congenital predisposition in short tail dogs because of underdeveloped levator ani muscle.

 Role of relaxin: relaxin is a polypeptide hormone which is thought to affect connective tissue components through a collagenase activity. In male, the primary site of synthesis is the prostate gland. Relaxin could be responsible for muscle atrophy and softening of connective tissue, which in turn could lead to PH formation. Relaxin receptor LRG7 was found to have significantly higher levels in the pelvic diaphragm muscles of dogs with PH compared with normal dogs. These findings suggest that relaxin might play a role in the pathogenesis of PH. Atrophy of pelvic diaphragm muscles may be attributable to increased relaxin activity.

Surgery

The standard surgical treatment for PH involves hernia repair using muscle transposition techniques. Superficial gluteal muscle transposition allows closure of the dorso-lateral defect, but filling of the ventral part is not easy and complication rates range from 15% to 58% with 36% recurrence rate. Internal obturator muscle transposition is the most reliable technique to close the defect. Complication rates range from 12 to 45% and recurrence rates range from 2.38 to 36% with this technique. Besides rupture of the pelvic diaphragm, associated lesions like rectal deviation or diverticulum, bladder retroflexion and prostatic disease contribute to the severity of the disease and may increase the incidence of recurrence.

Pexies

Pexies of abdominal organs have been reported as an adjunctive or sole treatment for PH. The long term benefits, complication rate and outcome of a 2-step repair protocol has been reported for bilateral or complicated PH.

PH was considered resolved in 90% dogs with a mean follow-up time of 26.6 months. Recurrence rate was 10% (4 cases) with all recurrences occurring within the first 6 months. No association was detected related to the type of associated lesions or abdominal procedure in recurrence of PH. Several advantages of abdominal pexies were reported. This prevent viscera from occupying the hernia, improving visualisation of anatomical structures and making repair easier, faster and more accurate. Subsequently damage to anatomical structures are less likely to happen, which may reduce the incidence of caudal rectal nerve or external anal sphincter damage reducing the incidence of post operative faecal incontinence. The shorter operative time may influence a low rate of post operative wound infection or dehiscence. In order to take advantage of the abdominal surgical time, some authors encouraged hernia repair to be performed as early as possible.

We completed a retrospective study including complicated and non-complicated PH where the surgical treatment was performed in 3 steps, laparotomy with abdominal organ pexies, castration and PH repair during the same operative time.

Materials and Methods

Medical records of dogs treated with the 3 steps in one procedure were reviewed between 1999 and 2006. Pre and post operative data included signalment, clinical signs, associated lesions, type of abdominal pexy performed, post operative complications, outcome and recurrence. The follow-up period ranged between 2 months and 3 years. Post operative examination was performed in each case 10 days and 6 weeks after surgery. Other follow-up information was obtained by phone contact with the referring veterinarians or with the owners.

Diagnosis was based on history, physical examination, radiographic and/ultrasonographic examination when necessary. Rectal palpation was performed to assess perineal diaphragm on both sides. Urinary catheterization was performed in order to assess patency of the urethra and monitor dieresis. Pre-operative assessment included blood biochemistry and hematology, ionogram and urinalysis.

The dogs were premedicated with ACP/morphine, ACP/methadone or diazepam/methadone combinations. Anaesthesia was induced with propofol and maintained with isoflurane or sevoflurane in oxygen. Epidural analgesia was performed with preservative free morphine and bupivacaine diluted with saline. Post-operative analgesia was performed with NSAID administration (carprofen or meloxicam), opioids (morphine or methadone) or CRI of fentanyl.

The dog was prepared for surgery. He was clipped ventrally from the caudal thorax to the pelvic region and on the perineal region on both sides. The rectum was emptied manually and a purse string suture was applied to the anus.

A laparotomy was performed first. The entire abdomen was inspected. The herniated organs were repositioned in their normal anatomical position. Depending on the associated lesions, a corresponding organ pexy was performed: colopexy in case of colo-rectal involvement, cystopexy, deferentopexy or prostatopexy in case of bladder retroflexion.

The dog was castrated.

A PH repair was performed using internal obturator muscle transposition (IOMT) in all cases. When bilateral herniation was diagnosed, bilateral IOMT was performed during the same procedure.

Each patient was hospitalized to monitor pain and recovery. He was discharged from the hospital when comfortable, able to eat and drink normally with no complications.

Post operative care at home included pain management with NSAID medication, antibiotherapy with clavulanate/amoxicillin/metronidazole for 8 days. Recommendations for wound care were given to the owner until suture removal.

Post operative complications, outcome, owner satisfaction were recorded when the dog was re-examined at 10 to 15 days for suture removal, at 6 weeks and 2 months to 3 years after the operation.

Results

Sixty five cases were included in the study. Eighty eight PH were operated. In 23 cases, PH was bilateral and both sides were operated during the same procedure. Six cases had PH operated on one side and had recurrence on the other side 6 months to 3 years after the initial surgery. Nine cases were operated because of recurrence of a previously operated PH; 4 had a muscle apposition technique and 5 had hernia repair with steel grid. Recurrence in those cases occurred 6 months to 4 years after the initial surgery. Three of the cases operated with grid insertion had associated fistulae related to foreign body reaction.

Several breeds of dogs were represented. Small breed dogs and medium size dogs were over represented; among them we had 16 Maltese, 6 Yorkshire terriers, 3 miniature spitz, 7 German or Belgian shepherd dogs, 4 Braque dogs. All the cases were intact males except 5 neutered males, 3 of them had previous surgery for PH repair. Age range was between 6 and 16 years old. Swelling of the perineal region and tenesmus were the most constant clinical signs. In 6 cases no swelling was evident at the time of consultation and the only clinical sign reported was tenesmus. A defect in the perineal diaphragm was detected by rectal palpation. Dysuria was present in 3 cases and urinary tract infection in 1 case. Rectal obstruction was present in 2 cases. Vomiting, shock, abdominal pain, melena were encountered in single cases. Associated lesions included:

 Rectal lesions: dilated or sigmoid rectum in all cases at initial presentation. Assessment of rectal lesions was subjectively performed by rectal palpation. True rectal diverticulum was present in one case.

 Urinary bladder retroflexion in 9 cases. Four cases had dysuria, one was in shock. Four cases had no urinary signs.

 Prostatic disease with evidence of prostatic enlargement, prostatic cysts or paraprostatic cysts at surgery in 12 cases.

 Small intestine herniation in 4 cases. Two cases had strangulated hernia with intestinal wall rupture.

 Localized megacolon in 2 cases.

 Apocrine gland cystadenoma with osseous metaplasia in 1 case.

 Concurrent anal gland abscess in one case.

During laparotomy we performed 41 colopexies alone, 12 colopexies and cystopexies, 3 colopexies and prostatopexies and 1 colopexy and deferentopexy.

The two dogs with ruptured bowel had enterectomy of the affected small intestine. Two other dogs had signs of local peritonitis. This condition was treated only by copious abdominal lavage.

All intact males were castrated after laparotomy.

In each case the patient was repositioned and the perineal region was prepared for surgery.

The perineal hernia was repaired using IOMT in all the cases. When a bilateral PH was diagnosed, bilateral IOMT was performed under the same procedure.

Post operative abdominal discomfort was the most frequent immediate post operative complication. It was present in 55% of the cases. Improved analgesia techniques decreased the incidence of post operative pain over the length of the study. When abdominal pain was present, the dog remained hospitalized. Duration for post operative hospitalization ranged between 24h and 3 days.

Other post operative complications were:

 Laparotomy wound infection and dehiscence in 1 case treated by debridement and resuture. One dog removed his abdominal sutures without any clinical consequences.

 Scrotal wound inflammation in one case.

 Perineal wound inflammation in one case.

 Failure in colopexy sutures with tear of the colon and peritonitis in one case. A laparotomy and enterectomy were performed. The dog died 15 days after surgery.

 Local peritonitis (Staph. aureus) was diagnosed 48h after surgery and was treated medically in one case.

Outcome

No recurrence of PH occurred on the operated side in all cases. In 6 cases, PH recurred on the opposite side 6 months to 3 years after the initial surgery. No defect in the pelvic diaphragm of the non affected side was detected at initial presentation for these cases.

Three dogs died during the follow-up period. In only one case, the death was related to post-operative complications (dehiscence of colopexy and laceration of the colon). Two other dogs died after urethral transitional cell carcinoma and nasal carcinoma.

Conclusion

The three steps surgical treatment for PH repair compares favourably with other techniques regarding post operative outcomes. The operative time is longer than when single laparotomy or PH repair are performed as a sole treatment. However this was not associated with an increased complication rate.