What is constipation?
Constipation is infrequent or difficult passage of stool or feces and is typically a temporary condition. Feces accumulate in the colon (large intestine). Many constipated cats experience straining or pain when attempting to defecate. Obstipation, a severe form of constipation, is often associated with a serious, permanent, or irreversible medical condition.
One of the major functions of the colon is water absorption, so sometimes the retained stool becomes hard and dry, which makes passing it even more difficult. In some cases, cats may become dehydrated.
Some constipated cats pass small amounts of liquid feces or blood because of excessive straining. Sometimes, the liquid feces are mistaken for diarrhea, but in fact it’s a small amount of liquid fecal material that squeezes around the hard fecal mass.
What causes constipation?
There are many potential causes of constipation in cats. Constipation is a condition seen most commonly in mature, middle-aged cats, although it may occur at any age. Common causes of constipation in cats include:
- Hairballs, especially in long-haired cats
- Eating irritating or indigestible substances, such as bones
- Obesity and/or lack of exercise
- Megacolon (enlarged colon) due to idiopathic (unknown) causes
- Neurologic diseases
- Painful conditions that make it uncomfortable to pass stool (e.g., osteoarthritis)
- Pelvic injuries that result in a narrowed pelvic canal
- Tumors or masses in the colon or rectum
- Any disease or condition that results in dehydration
What is megacolon?
Megacolon refers to a dilated and weak colon that causes severe constipation. Megacolon is the most common cause of constipation in cats. In this condition, the weakened muscles of the colon fail to propel fecal matter out of the colon, due to neurological impairment, problems with the muscles lining the colon, or both.
Megacolon may be seen as a primary condition or secondary condition following long-term constipation. When the colon becomes distended with fecal material over an extended period, its ability to contract may be reduced or lost, resulting in megacolon. Feces then accumulate in this abnormally distended and enlarged colon.
What are the signs of constipation?
Most cats produce feces about once a day, and many have bowel movements that correspond with daily feedings. If your cat is constipated, they will probably attempt to pass feces several times, unsuccessfully. Alternatively, they may only pass small, hard, dry feces or produce a very small amount of watery feces with or without mucus. You may see them go in and out of the box frequently, similar to when they have urinary disorders. They may strain or vocalize in the box, or even defecate outside the box.
Other signs of constipation may include decreased appetite, lethargy and vomiting. Call your veterinarian if your cat fails to produce a bowel movement within 48 to 72 hours of a previous bowel movement.
How is constipation diagnosed?
Most cases of constipation are diagnosed through physical examination and medical history. Unless your cat is obese or tense, your veterinarian can often palpate (feel) the accumulated fecal material in the colon. In many cases, they will perform abdominal X-rays to determine the extent of constipation and whether there is an obstruction.
Blood tests and urinalysis are valuable to search for dehydration, infection, or other conditions that can predispose the cat to constipation. In advanced cases, an abdominal ultrasound may help identify the cause of your cat’s constipation. Biopsies may also be recommended if a rectal mass or stricture is suspected.
How is constipation treated?
Treatment varies depending on the cause of constipation. If an obstruction such as a colonic tumor is present, surgery may be required.
Most cases of constipation are relatively easy to treat if caught in the early stages. The first step is to loosen or remove the impacted, hardened fecal matter. Removal may be accomplished using one or a combination of therapies, including enemas, manual removal and medications. Laxatives such as dioctyl sodium sulfosuccinate (DSS) or polyethylene glycol (PEG) 3350 are commonly prescribed.
Depending on your cat’s condition, your veterinarian may recommend manual extraction of feces from the colon under general anesthesia, as well as hospitalization for intravenous fluid therapy needed to correct fluid imbalances and dehydration that can worsen constipation. A feeding tube may be placed to deliver a constant infusion of a laxative to soften the stool. Cats with megacolon often require multiple days in the hospital for treatment.
If constipation recurs or becomes a long-term problem, dietary management or medications may be needed to prevent recurrence. Several treatments are available to soften the feces and promote regular bowel movements. In mildly affected cats, high-fiber diets, lubricating laxatives, stool softeners or probiotics may prevent recurrence.
More severely or chronically affected cats may need drugs that stimulate contraction of the colon (cisapride). Before using these drugs, an obstruction must be ruled out. The dose of these drugs is adjusted to produce the desired effect. Ideally, cats should defecate at least once every other day. Over time, the cat may develop resistance to the treatment and medication, necessitating an increase in the drug dosage or a change in therapy. Do not make changes to your cat’s treatment protocol without consulting your veterinarian.
Make sure there is always access to a clean litter box to encourage frequent defecation. In long-haired cats, regular grooming may reduce hair ingestion, while “hairball remedies” or hairball diets may lessen the likelihood of hairballs causing constipation.
When might surgery be necessary?
If constipation is severe and medical treatment is unsuccessful, surgery may be recommended. Surgical treatment involves removal of the affected portion of the colon, a procedure called a partial or sub-total colectomy. This is often a referral procedure performed by a specialist surgeon. The recovery period can be prolonged, and side effects can occur following this surgery, but most cats do well.
What is the expected outcome for constipation?
The long-term outlook varies according to the cause of constipation; however, most cats can be adequately managed without surgery and resume normal, healthy lives. For cats that require surgery to correct megacolon, the prognosis is generally good.
