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===Diagnostic Imaging===
===Diagnostic Imaging===
This is not necessarily required but radiography or ultrasonography may be useful to determine whether or not the bladder, prostate or small intestine are within the hernial sac. A positive contrast cystogram can be performed to better define the location of the bladder.
This is not necessarily required but '''radiography''' or '''ultrasonography''' may be useful to determine whether or not the bladder, prostate or small intestine are within the hernial sac. A '''positive contrast cystogram''' can be performed to better define the location of the bladder.
==Treatment==
==Treatment==
Perineal hernias may be treated conservatively by altering the animal's diet but they are often corrected surgically.
===Conservative Management===
This involves the follwoing aspects of treatment:
*A '''diet with a high fibe content''' to icrease the bulk and moisture content of the faeces and reducing the likelihood of constipation and faecal tenesmus.
*'''Laxatives''' to increase the moisture content of the faeces. Various products are used, including '''lactulose''', '''psyllium mucilloid''' and '''dioctyl sodium sulphosuccinate''', a cathartic which increases the rate of secretion of fluid from the intestinal mucosa.
*Actual or 'chemical' castration using '''delmadinone acetate''', which reduces the concentration of circulating androgen hormones. Androgens and their receptors are involved in the aetiopathogenesis of perineal hernia and castration will also prevent most prostatic diseases (with the exception of prostatic neoplasia).
*'''Occasional enemas or manual evacuation of faeces''' can be performed to relieve any constipation and to remove any faeces that have become impacted in rectal sacculations or diverticula.
===Surgical Management===
====Surgical Techniques====
Surgical intervention is indicated if medical treatment has failed or if herniated organs become incarcerated or strangulated. Two major techniques have been described to achieve herniorraphy.
*An '''internal obturator transposition herniorraphy''' is most commonly performed with the animals positioned in sternal recumbency with extended hips (as for surgery of the anus, anal sacs or vulva). An incision is made dorsoventrally, parallel to the median plane on the affected side and the hernial sac is identified and entered. The herniated organs are identified and their viability is assessed before they are returned to the abdominal or pelvic cavity. The incision is extended to reveal the internal obturator muscle which originates on the dorsal surface of the ischiatic table and runs over the lesser sciatic notch to insert on the greater trochanter of the femur. The muscle is mobilised from the ischium using a periosteal elevator, moved dorsally and sutures are then passed between the it, the coccygeus and levator ani muscles and the external anal sphincter. The sutures should be pre-placed before they are tied and care should be taken to ensure that they do not penetrate through to the rectal lumen. The tendon of the internal obturator may be sectioned to enable the muscle to be transposed but care should be taken not to damage the '''sciatic nerve''' which runs beside it over the sciatic notch. The procedure can be performed bilaterally but, since the procedure increases the degree of faecal tenesmus, an interval of 4-6 weeks is often intermitted before the contralateral repair is completed.
*The '''traditional herniorraphy''' is a simpler version of the above technique, in which sutures are placed between the external anal sphincter, coccygeus and levator ani without elevating the internal obturator muscle. Since the internal obturator is not elevated to fill space created by the hernia, the sutures placed in this technique are usually under greater tension and they may cause deformity of the anus.
*'''Castration''' should be undertaken at the same time as this reduces the risk of recurrence of 2.7 times.
*Other procedures may be performed to prevent abdominal organs from moving into the hernia, including a '''ductus deferopexy''' where the bladder is tethered to the ventral abdominal wall by the transected ducta deferentia and a '''colopexy''' where the descending colon is attached to the left body wall, preventing rectal prolapses and severe rectal dilations.
====Post-operative complications====
The following phenomena may be observed post-operatively:
*'''Tenesmus''' may worsen in the immediate post-operative period, especially if the anus has been deformed by the herniorraphy and this may even lead to '''rectal prolapse'''. The condition can be managed by softening the faeces (as described above) and placing an anal purse-string suture in the case of rectal prolapse.
*'''Neuropraxia''' of the sciatic or caudal rectal nerves may occur. The caudal rectal nerves are most often damaged as they run along the dorsal surface of the internal obturator muscles, lateral to the coccygeus and levator ani. Damage to the nerves results in temporary or permanent faecal incontinence. If there are signs of sciatic nerve paralysis, the offending sutures must be removed immediately.
*'''Urinary incontinence''' may occur if the bladder is retroflexed and its nervous supply damaged.
*'''Surgical wound infections''' may occur, especially if any sutures have penetrated the rectal lumen.
==Prognosis==
==Prognosis==
The rate of recurrence is around 15% one year after surgical herniorraphy. Cases involving bladder retroflexion have the poorest prognosis and, although cases managed medically may have an acceptable quality of life, there is always a danger that the bladder or another organ will be incarcerated and strangulated in the hernial sac.