Normally, the pelvic diaphragm will allow for rectal support and to keep the abdominal contents from encroaching on the rectum. When the pelvic muscle diaphragm structures weaken, pelvic and caudal abdominal contents (rectum, bladder, and small intestine) may be pushed caudally into the perineal region. Chronically herniated contents invariably lead to muscle deterioration in the area between the external anal sphincter, the levator ani, and coccygeal muscles. This progressive shrinkage of muscle fibers is possibly associated with imbalances of gonadal hormones, such as estrogen, androgen, and relaxin, related to prostatic hypertrophy.
Weakness in the coccygeal and levator ani muscles is commonly in aging male dogs. Perineal hernias have rarely been reported in females and this may be associated with pregnancy when pelvic diaphragm muscles weaken.
Clinical signs include a perineal swelling, straining to defecate and intermittent constipation. In young dogs, perineal hernia can present at young as 4 months of age, with significant herniation of pelvic organs. In older dogs, a rare complication such as megacolon may be observed radiographically.
The perineal swelling is usually obvious and may be unilateral or bilateral. Chronic tenesmus may lead to caudal displacement of the prostate and urinary bladder.
Temporary alleviation may be obtained from conservative management including the use of stool softeners, periodic enemas and digital fecal removal. However, most cases require surgical treatment to prevent life-threatening complications from the incarceration of herniated organs, especially the urinary bladder.
Treatment is recommended in severe cases and owner discretion is used in cases where only mild herniation is present as these cases may only required medical therapy.
Severe cases usually requires surgical intervention and a number of procedures are available, although reherniation is a common recurrence. Among the techniques attempted to avoid reherniation, transposition of the internal obturator muscle is the most reliable technique and considered now the conventional herniorrhaphy. The transposed muscle increases strength of the ventral perineum where most hernias occur.
- Lee AJ et al (2012) Use of canine small intestinal submucosa allograft for treating perineal hernias in two dogs. J Vet Sci 13(3):327-30
- Pérez-Gutiérrez JF et al (2011) Epidermal growth factor and active caspase-3 expression in the levator ani muscle of dogs with and without perineal hernia. J Small Anim Pract 52(7):365-370
- Dorn AS et al (1982) A preliminary comparison of perineal hernia in the dog and man. J Am Anim Hosp Assoc 18:624–632
- Merchav R et al (2005) Expression of relaxin receptor LRG7, canine relaxin, and relaxin-like factor in the pelvic diaphragm musculature of dogs with and without perineal hernia. Vet Surg 34(5):476-481
- Niebauer GW et al (2005) Relaxin of prostatic origin might be linked to perineal hernia formation in dogs. Ann N Y Acad Sci 1041:415–422
- Bellenger, CR & Canfield, RB (2002) Perineal hernia. pp:487-498. In: Textbook of Small Animal Surgery. 3 rd ed. (Slatter, D. ed.), Saunders, Philadelphia
- Sontas BH et al (2008) Perineal hernia because of retroflexion of the urinary bladder in a rottweiler bitch during pregnancy. J Small Anim Pract 49(8):421-425
- Vyacheslav H & Ranen E (2009) Perineal hernia with retroflexion of the urinary bladder in a 4 month old puppy. J Small Anim Pract 50(11):625
- Bojrab, MJ & Toomey, A (1981) Perineal herniorrhaphy. Compend Contin Educ Vet 3:8-15
- Pratummintra K et al (2012) Perineal Hernia Repair Using an Autologous Tunica Vaginalis Communis in Nine Intact Male Dogs. J Vet Med Sci Nov 6
- Spreull, JS & Frankland, AL (1980) Transplanting the superficial gluteal muscle in the treatment of perineal hernia and flexure of the rectum in the dog. J Small Anim Pract 21:265-278
- Chambers, JN & Rawlings, CA (1991) Applications of a semitendinosus muscle flap in two dogs. J Am Vet Med Assoc 199:84-89
- Thiel C et al (2010) Surgical therapy of perineal hernia in dogs by the use of Small Intestinal Submucosa (SIS™): a retrospective study. Tierarztl Prax Ausg K Kleintiere Heimtiere 38(2):71-78
- Bongartz, A et al (2005) Use of autogenous fascia lata graft for perineal herniorrhaphy in dogs. Vet Surg 34:405-413
- Clarke, RE (1989) Perineal herniorrhaphy in the dog using polypropylene mesh. Aust Vet Pract 19:8-14
- Vnuk, D et al (2006) A modified salvage technique in surgical repair of perineal hernia in dogs using polypropylene mesh. Veterinarni Medicina 51:111-117