Constipation is defined as infrequent or difficult defecation of hard, dry feces, with retention of stool in the colon and/or rectum. It is an occasional, harmless problem in most cats. Repeated bouts of constipation, however, is an abnormal finding and, left untreated, constipation can progress, with sometimes dire consequences.
What can cause it
There are many potential causes of feline constipation.
✔ Dehydration is a prevailing cause, and diseases that predispose a cat to dehydration (diabetes, kidney disease, overactive thyroid) can be a factor in constipation.
✔ Arthritis can contribute to constipation because affected cats may have difficulty getting to their litter box, leading to stool retention (or difficulty getting to their water bowl, leading to dehydration).
✔ Sudden change in diet, for example, a cat who has suddenly switched from canned food to dry food, can lead to constipation.
✔ Ingestion of large amounts of hair from overgrooming.
✔ A dirty litter box may dissuade cats from using it, promoting retention of stool and constipation.
Other possible causes include anything that can result in an obstruction of the passage of stool through the colon, such as a tumor. In most cases, however, an inciting cause cannot be identified.
Don’t miss these signs
Signs of constipation can vary. Some cats show minimal signs, and the condition is discovered when the owner notices a lack of stool when tending to the litter box, or notices very small, firm, dry stool in the box. (Most cat stool is moist enough so that cat litter will stick to it. Constipation usually results in stool that is so dry that litter won’t adhere to it.)
Other cats will visibly strain to defecate. They crouch over their litter box, staring straight ahead, occasionally →
crying out in discomfort, pushing hard with their abdomen as they try to expel impacted feces.
Diagnosing constipation is usually based on the cat’s history, clinical signs and physical examination. An X-ray of the colon may be performed to confirm the diagnosis and assess the severity of the constipation.
How to help
Treatment depends on the severity of the condition.
✤ Rehydrating the cat and maintaining hydration is a key component of therapy. Adding warm water (or water with added tuna juice) to a canned diet creates a broth, which cats can lick up, and may be an effective way to sneak more water into the diet.
✤ Laxatives may be warranted. They increase the water content of the stool and help lubricate the stool so that it passes more easily.
Dietary modification usually involves:
✤ Switching to a canned diet (if the cat is currently eating dry food)
✤ Adding fiber to the diet. This can be done by mixing a source of fiber into the cat’s regular diet (bran or psyllium) or by feeding a prescription diet that has already been formulated to have additional fiber.
Canned pumpkin is a good source of fiber and although cats are true carnivores, a surprisingly high number of cats don’t mind the taste of it and will eat food to which one or two tablespoons of pumpkin has been added.
✤ Low-residue diets are prescription diets that have been formulated to be very highly digestible. The majority of the diet is digested and absorbed, leaving very little undigestible material behind. This results in smaller stools, which may be easier for constipation- prone cats to eliminate.
✤ Prokinetic agents — drugs that increase the motility of the colon — may be warranted in more severe cases, especially if the veterinarian suspects that a defect in colon motility is contributing to the problem.
Most cases of constipation in cats are mild and temporary. However, if you see your cat straining to defecate, notice very firm, hard dry stools in the litter box or believe your cat hasn’t defecated in the past 48 to 72 hours, a visit to the veterinarian is
warranted.
Monitor for Megacolon
When constipation persists or fails to respond to treatment, the disorder may progress, leading to a condition called megacolon, in which the colon becomes enlarged and dilated, and unable to contract and propel the stool with as much force as before.
Mild or moderate cases may respond to higher doses of the treatments described above (laxatives/stool softeners, prokinetic drugs, dietary fiber), but as things progress, the occasional enema may be necessary. This involves putting liquid into the colon, to increase the water content of the feces and stimulate the colon to contract, promoting elimination.
Although owners can be trained to administer enemas to their cat at home, most cats are (understandably) not very compliant, and the procedure is usually performed by trained staff in the veterinary office. Unfortunately for cats with megacolon, the need for enemas often becomes more frequent until cats no longer respond to any medical therapy at all.
At this point, surgical treatment becomes the only option. The surgery, called a subtotal colectomy, involves the removal of the majority of the colon. Although this is a major surgery, the majority of cats respond well to the procedure. Post-operatively, a significant number of these cats will have diarrhea; however, after a few weeks, most cats begin to produce stool of an acceptable consistency, and life returns to normal.
In my career, I’ve probably referred about 10 cats to a referral center for this surgery, and the vast majority responded well.