Current Accepted Surgical Techniques:
- Muscle flap from the pelvic floor (internal obturator muscle flap) perineal hernia repair, complex and requiring advanced surgery. Performed at Findon Vet Surgery since 1994. See Diesel's Perineal Hernia Repair
- Muscle flap from caudal thigh hamstring (semitendinosus muscle flap) perineal hernia repair. Very advanced procedure reserved for patients who have irrepairably damaged a prior obturator procedure. Performed by the Findon Vet Surgery since 2000 and was supposedly the first of this operation performed in Australia.
- NOT acceptable is an old technique that simply places sutures from the sacrotuberous ligament to muscles of the anus. It has an extremly high failure rate.
- Please contact the Findon Vet Surgery if need more information about perineal hernia repair surgery.
A perineal hernia is when the contents of the abdomen herniate (are pushed through a tear in the peritoneum - the lining of the abdomen) BACKWARDS through the pelvic canal, and out by the side of the anus! It sounds aweful, and it certainly is as bad as it sounds.
Before there is an actual perineal hernia, there is constant straining due to constipation. The most common cause is a chronically enlarged prostate in and entire older male (un-castrated, un-desexed) dog which blocks the passage of the stools through the pelvis. The prostate sits under the lower large bowel (the colon) and rectum, inside the pelvic canal. Initially this straining causes a lesser problem called rectal sacculation, and is a bulge in the rectum - a stretching of the rectum - and this fills with faeces. So much faeces gets trapped here that it just gets bigger and bigger, with the poor dog straining more and more as he can't get the stools out.
Eventually this straining is so severe that the pressure in the abdomen from the poor dog straining is great enough to push organs and other contents form the abdomen back through the pelvis to end up next to the swollen rectal sacculation. The only solution is major surgery. Firstly just the floppy omentum tissue, a web like net structure in the abdomen, is pushed though a tear in the peritoneum. Then the bladder is pushed backwards and ends up bulging next to the bottom! In a couple of dogs I have found intestines, and also one had a large prostatic abscess!
The current accepted procedure for repair of a perineal hernia is a muscle flap utilising the internal obturator muscle from the floor of the pelvis. This muscle is freed up and isolated from its insertion on the femur, and then reflected up and used effectively to plug the gap by suturing it to the strong sacroiliac ligament to the outer top side, and to the muscles of the anus (the coccygeus,levator anis and anal sphincter muscles).
An early technique that just uses sutures from the ligament to the anus muscles has not been recommended for this repair since the 1990's due to frequent breakdown. I have repaired a few of these over the years using the obturator muscle flap technique.
If the obturator muscle flap surgery beaksdown, then another muscle flap from the back of the thigh, the semitendinosus muscle, is reflected up and uner, and partly around the anus to repair the heria. This was first performed in Australia by myself around 1999 or 2000 - as advised by a small animal surgical specialist who sent me the details on the procedure after it had been performed on five dogs in the USA!
CASTRATION is advised at the time of the perineal hernia repair surgery. An enlarged prosteat is by far the most common contributing cause of constipation and desexing an entire undesexed male dog is necessary to remove the source of testosterone (male sex hormaone) which stimulates activity in the prostate and its subsequent enlargement.
An enlarged prostate sometimes is the result of prostate cancer, a prostatic cyst or prostatitis due to infection. Prior to perineal hernia repair surgery, the prostate must be examined thoroughly and usually includes a fine needle aspirate biopsy to determine what underlying prostate disease is present. In the case of a highly malignant prostatic cancer, repairing the hernia is unlikely to be of benefit - however, some prostatic cancers resolve due to pathologists being unable to accurately predict the cancer's growth behaviour as a result of prostatic cells showing varying characteristics that are almost impossible to interpret.
Indeed I once had a large entire male rottweiler whose results came back as a highly malignant prostate cancer. We did not euthanase this dear old fellow (and he didn't have a perineal hernia - just rectal sacculation) but instead castrated him and treated him with anti-male hormaone treatment, and strong antiinflammatory drugs to give him some comfort and quality of life - which we expected to end in weeks. BUT he responded magnificently. The tumour shrank withOUT any chemotherapy and he liver for a few more years without any recurrence of a prostate problem at all and died at an old age!!!! Thus is the nature of prostate cancer - unpredictable!
All dogs presenting with a large bulge next to their anus should have an ultrasound performed to check the contents of the mass, to check if it is a perineal hernia, a tumour (cancer) or other (abscess or cyst, or benign growth).