Constipation and Megacolon in Cats

Laurie Anne Walden, DVM

Photo by Zoë Gayah Jonker

Constipation in a cat should never be ignored. Most cases of constipation are mild and last only a day or two. But cats with long-term or repeated bouts of constipation are at risk for more serious medical problems.
 
Constipation is the infrequent or difficult passing of feces. Because the colon removes water from intestinal contents, feces that stays in the colon becomes hard and dry. In time, as more feces accumulates in the colon, the mass of hard feces gets too large to pass through the pelvic opening. This more severe form of constipation, when feces can’t pass at all, is called obstipation. A cat with obstipation has to be treated in the hospital to get the impacted feces out of the colon.
 
Some cats with chronic (long-term) constipation and obstipation develop megacolon, a distended colon that no longer works properly. The colon wall becomes stretched and limp, so it can’t push feces toward the anus. Treatments that help relieve constipation don’t work as well for megacolon, so cats with megacolon might need surgery.
 
Some of the many causes of constipation are medical disorders, medication side effects, obstruction of the colon (for example, by tumors or pelvic fractures), and ingested foreign material. Dehydration makes constipation worse. Cats that avoid the litter box because of orthopedic pain or stress—conflict with another cat, change of routine, illness, and so forth—can develop constipation. Megacolon can be caused by abnormal nerve control of the colon muscles (something the cat is born with).
 
Symptoms
A cat that is squatting and straining in the litter box might or might not be constipated. Male cats with urinary blockage, which is a medical emergency, also squat and strain. Animals with diarrhea have an increased urge to defecate but might pass only a little bit of liquid stool. Urinary blockage, diarrhea, and constipation can all result in a cat squatting in the litter box, looking uncomfortable, and not producing much of anything.
 
The symptoms of constipation depend on the duration and cause and whether it has progressed to obstipation and megacolon:

• Small, hard, dry stool
• Stool produced less frequently than usual
• Straining to defecate
• Belly discomfort
• Decreased appetite
• Decreased activity
• Vomiting

 
Diagnosis
A large amount of feces in the colon can be found with physical examination or radiographs (x-ray images). Other diagnostic tests are used to find the cause of constipation and assess the overall health of the patient. Megacolon is diagnosed with radiographs.
 
Treatment
Chronic constipation tends to become less responsive to treatment over time. The type of treatment depends on the cause and severity of constipation. Treatments for constipation include increased hydration, laxatives, medications to increase intestinal movement, enemas, and a modified diet (which could be a high-fiber diet or a low-residue diet depending on the individual case). Never give a cat a laxative or enema unless your veterinarian has specifically recommended it; some human products aren’t safe for cats.
 
For cats with obstipation, the impacted feces must be removed in the hospital. One method is to remove the feces manually while the cat is under anesthesia. A newer method involves placing a tube through the nose into the stomach (cats tolerate this surprisingly well) and infusing a solution over several hours to break down the mass of feces so it can pass.
 
Megacolon is managed at first with the same treatments used for constipation. If those treatments no longer work, megacolon can be treated by surgical removal of the colon. Most cats do well after this surgery.
 
Photo by Zoë Gayah Jonker on Unsplash

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