The most common sign associated with megacolon is frequent constipation.

Treatment starts with medical therapy and only when this fails is surgical intervention considered.

Following surgery, diarrhea may be initially present, but frequently resolves within a two month period of time.

The prognosis for most patients is generally good, because they are able to lead a much more comfortable life.

What is Megacolon?

• Mega = big; colon= large intestine
• It is a disease of the colon, also known as large intestine, which results in distention of the colon with stool. The end result is constipation. 
• There are two different forms of megacolon: congenital and acquired.  The congenital form is an abnormality of the colon at birth.  Congenital does not necessarily mean that it is inherited (in that it is passed through genes from the parents to offspring), but this can be the case.  The acquired form is the more common of the two.  The most common acquired form is known as idiopathic, which means the cause for the disease has not known. 
• There are many different causes of megacolon that have been proposed.  Some factors that contribute include the patient’s diet and what the patient’s environment consists of. 
  • If the litter box is frequently dirty, a cat may refuse to have bowel movements on a regular basis. The result may be chronic distention of the colon with stool, which could result in megacolon.
  • Ingested foreign bodies such has bones may also become impacted in the colon and result in megacolon. If the obstruction is not quickly relieved, permanent damage may occur. 
  • Other diseases that could potentially lead to a megacolon are those that result in a narrowing of the rectum or anus making it difficult to pass stool.  Examples of diseases that can cause a narrowing are: tumors narrowing the pelvic canal, anal sac abscess, fractures of the pelvis, or neurologic disease.

Clinical Signs

• Megacolon is most commonly seen in cats, but it can be found in dogs too.  It most typically is found in middle-aged, male, domestic shorthair breeds.
• Stools may appear smaller than normal; in some cases the stools may be very large
• Less frequent productive bowel movements
• More trips to the litter box, which are not productive
• Straining to defecate, or painful defecation
• Dry or hardened stool
• Intermittent blood in feces
• Decreased appetite or anorexia
• Depression/ lethargy
• Weight loss
• Dehydration
• Abdominal pain
• Vomiting
• Anemia

Diagnosis

• Sometimes all that needs to be done to arrive at a diagnosis of megacolon is a good history and physical exam (including a rectal exam).
• Abdominal radiographs (x-rays) are very useful to identify the extent of the megacolon and identify an underlying cause of the megacolon such as a previously fractured pelvis.
• CBC (complete blood count), chemistry,  urinalysis, and T4 (testing for thyroid disorders) should be done on all older patients that have megacolon. The results of the blood work may not help to identify the cause of the megacolon, but may identify other concurrent problems that need to be addressed.
• Other tests that may need to be performed in order to accurately diagnose the cause of megacolon may include abdominal ultrasound or colonoscopy.
  

Treatment

• After the patient is evaluated, there are many treatment options that can be tried.  It is recommended that each patient start with medical management before surgery is performed.
  • Medical management
    • Laxatives or lubricating agents
    • Water enemas
    • Manual removal of stool under anesthesia
    • Diet change to foods with higher fiber content
    • Drugs that increase motility of the large intestine - cisapride
  • Surgery
    • Removal of the colon
    • The end of the small intestine is connected to the rectum
      

Potential Complications

• Short-term
  • Leakage of feces at the suture line of the intestine can lead to a severe infection in the abdomen.
  • Straining can still take place during the first week after surgery.
  • Cramping of the intestines may be evident by signs of suddenly running, sudden meowing and licking flank or belly. These cramps frequently resolve with time; bacterial overgrowth can lead to gas buildup. Medication can be used to help reduce the number of bacteria in the intestine.
  • Loose stool and increased number of bowel movements following surgery is common. Over the next 2-3 months the stools will start to firm. Stools usually do not become perfectly normal, but usually will be soft, formed stools.
• Long-term
  • About 30 to 50% of cats will have increased frequency of bowel movements and softer feces for life.
  • Bacterial overgrowth can be a complication that requires long-term treatment.
  • Recurrence of the megacolon is possible, but is not common.
  • Incontinence of feces is an uncommon problem after surgeryand usually is caused by a weak valve in the anus (anal sphincter). The anal sphincter could become damaged from chronic over distention by the impacted feces.

Aftercare

• Antibiotic may be prescribed at the disgression of your pet's surgeon.
• Pain medications (analgesics) are prescribed to minimize discomfort.
• Laxatives are usually discontinued after surgery.
• Highly digestible diets are recommended for the remainder of the patient's life.
• The anal region may need to be cleansed with "baby wipes" and Vitamin A/D ointment applied to the anal region if your pet has diarrhea.
• It’s often useful to have multiple litter boxes to avoid accidents after surgery.
• Activity should be restricted for 3 weeks after surgery to allow for proper healing of the incision.
• The patient should be evaluated daily for signs of infection of the incision which include the following: redness, swelling, pain, or discharge from the incision.

Prognosis

• The prognosis for most patients is generally good, because they are able to lead a much more comfortable life.

< Back to Article Index | Top of Page

What is a Board-certified surgeon?

Click here to find out!