A “hernia” is an abnormal hole in between any of the muscles of the abdominal cavity where internal fat and organs can become trapped. The perineum is the area surrounding and supporting the anus and genitals.
How is a Perineal Hernia diagnosed?
Physical exam - rectal examination is required to confirm the diagnosis of perineal hernia and rule out other causes of perineal swelling such as anal gland disease.
Abdominal X-rays - some patients may require abdominal x-rays to evaluate for organ herniation
Abdominal Ultrasound - sometimes ultrasound of the abdomen and hernia is helpful in determining whether emergency surgery is required or not.
Blood work - this information is used to develop the safest anesthesia and pain management plan for the patient
How is a Perineal Hernia treated?
While less common, some dogs can present with severe disease and organ entrapment require emergency stabilization with fluid therapy and possibly urinary catheterization before surgery. Surgery is performed once the patient is stable for anesthesia in order to free the entrapped organs and remove any unhealthy tissues. Neuter is always performed. Hernia repair may or may not be performed at the same time, depending on how stable the patient is. These patients typically present with a firm, painful perineal swelling, and signs of systemic illness such as vomiting and lethargy.
Three muscles within the perineum called the “pelvic diaphragm” create the abdominal wall on the tail end of dogs and cats. When the muscles of the pelvic diaphragm weaken, a hernia can develop where abdominal contents can slip through the muscles and bulge in the spaces on either side of the anus. Sex hormones in male, intact dogs can cause significant weakening of these muscles over time. This is why >95% of perineal hernias are seen in older male, intact dogs and far less common in females or dogs neutered at a younger age. Dogs with perineal hernia develop a swelling on either or both sides of the anus and often present for straining to defecate or constipation. The severity of clinical signs depends on the size of the hernia and whether or not any organs have become trapped inside. Many dogs only have abdominal fat inside the hernia, but in some dogs the intestine, bladder, and/or prostate can become trapped within the hernia and become strangled. Dogs with larger, loose hernias may be less likely to strangulate any herniated organs, so some dogs may only have mild straining to defecate while others may have painful, life-threatening organ entrapment requiring emergency surgery. Whether or not the hernia is an emergency is best decided by your veterinary care team after thorough examination and diagnostics.
Here are some of the possible clinical signs to suggest perineal hernia:
Soft, pain-free swelling on one or both sides of the anus
Hard, firm, painful swelling on one or both sides of the anus (may suggest organ entrapment emergency)
Straining to defecate or difficulty pooping
Straining to urinate (may suggest bladder entrapment)
Vomiting, lethargy (usually only in severe cases)
Surgical Treatment for a Perineal Hernia
Surgical repair is the treatment recommended for perineal hernia to eliminate the risk of organ entrapment down the road. Surgical repair of a perineal hernia is called perineal herniorrhaphy. Unfortunately, the weakened muscles of the pelvic diaphragm are not robust enough to hold sutures for repair on their own, so neighboring muscles are used to patch the hole in the pelvic diaphragm. In patients with organ entrapment or severe perineal hernia, abdominal surgery is also required to free the entrapped organs, remove unhealthy tissue, and possibly tack the bladder and colon in place to prevent their herniation. Neuter is also performed in all intact patients to reduce the prostate size and remove the hormones responsible for weakening the pelvic diaphragm muscles. There is a good prognosis after surgery, however up to 10-15% of dogs can re-herniate, especially those that strain to defecate early after surgery before healing occurs. To reduce this risk, all dogs with perineal hernia are started on stool softeners at least a week before surgery and are continued on stool softeners for at least 1 month after surgery.
Medical Management of a Perineal Hernia
Initially, most dogs have mild to moderate clinical signs such as perineal swelling and straining to defecate. These patients may benefit from medical management with stool softeners (eg. lactulose, miralax) and high fiber diets to make defecation easier and reduce straining which can enlarge the hernia over time. Some dogs can be successfully medically managed for the rest of their lives. However, it is important to understand that dangerous organ entrapment can occur at any time from patient activity or changes in hernia size. So part of medical management is a commitment to daily at-home monitoring of the perineal swelling for any changes in size, firmness, or pain which should be communicated to your veterinary care team. Additionally, the sooner the hernia is repaired, the greater chance of a successful outcome. Some dogs may fail to respond to medical management or worsen over time and require surgical repair of the hernia.
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