Feline Constipation: Megacolon

As I am writing this, the weekend is now over only after enjoying a lovely brunch with my sister at Waverly Place. My brunch strategy is to first survey the menu and make my main course selection based on my dessert choice and then work backwards. This methodology is a reflection of dinner time in my formative years when everyone asked what was for dessert before we even ate the main meal. My siblings and I then ate the main meal accordingly to save room. My mother, having a master’s degree in human nutrition from Cornell University, was big on healthy eating with the exception of dessert. Then all bets were off the table. 

I think I made a good choice!

When asked what my perfect last meal would be,  without question it would be the dessert buffet at a church social. I would pull up a chair and help myself to EVERYTHING! Unfortunately, there is a price to pay for such gluttony. There certainly is a long list of jokes in our society about feeling full, bloated, and uncomfortable. But for many cats, it is no joking matter to be constipated.

WHAT IS THE PURPOSE OF THE COLON SECTION OF THE INTESTINAL TRACT?

The colon is the section of the intestinal tract from the small intestine to the rectum. It stores poop and removes extra water and salt. It can actually store several weeks worth of stool. Many pets commonly will not have a bowel movement for 1 to 2 days after an anesthetic procedure.   Unfortunately, in other cases, the longer the feces remain in the colon, the more water that is removed which leads to feces becoming very firm and dry. As the colon becomes constipated, this can lead to dilation more than double its normal diameter. This end stage of chronic impaction and extreme dilation is called Megacolon in cats. 

THERE MUST BE MANY CAUSES. WHICH ONES ARE MOST COMMON?

 Many theories abound as to the causes: dry cat food, inactivity, excessive grooming/hair impaction, certain medications, electrolyte imbalance/kidney disease and decrease in water consumption. Anatomical causes include nerve injury, Manx/bob tail spinal cord abnormalities, and fractures/narrowed diameter of the pelvic (hip) canal. are also causes. The majority of Megacolon episodes appear to have an unknown cause (idiopathic).  It is suspected there is a lack of muscle wave (peristalsis) motion of fecal material moving through the colon. 

 ARE THERE SIGNS NOTED BY OWNERS?

Although occasional episodes are not reason for alarm, most cat parents report a decrease of poop in the litter box accompanied by absent, prolonged, or painfully difficult defecation. The passed poop may be dry or hard although some report mucous or soft stool with a bloody tinged that may reflect material being passed around the firmer poop. It often advances to lack of appetite, vomiting and weight loss. Some may appear to have difficulty urinating. 

HOW IS CONSTIPATION TREATED ONCE IT IS DIAGNOSED BY PHYSICAL EXAM ALONG WITH RADIOGRAPHS?

Mild cases are treated with special diets such as Royal Canin fiber responsive cat food following warm water enemas. Other cats do better with low residue, canned diets.  In addition, stool softeners (canned pumpkin, bran cereal, Metamucil, Konsyl, Miralax, Dulcolax) and medications that improve gut motility (pro-kinetic agents) are often prescribed. 

TELL ME MORE ABOUT THE PRO-KINETIC MEDICATIONS AVAILABLE TO ALLEVIATE CONSTIPATION.

Cisapride improves motility of the colon. It was previously used for reflux in humans, including babies. Currently, cisapride can only be obtained from compounding pharmacies. It will not be effective if intestinal nerves have become nonfunctional. Another medication, Tegeserod, works in a similar fashion.  

WHAT OPTIONS ARE RECOMMENDED IF MEDICAL THERAPY FAILS?

Removal of the colon (called a Subtotal Colectomy) is recommended, although many will have persistently soft stools postoperatively. 

Betsy Sigmon DVM, Diplomate ABVP Canine & Feline

Creature Comforts Animal Hospital

Cary, NC