Being constipated is no fun. Being constipated repeatedly is even less so. At the Animal Clinic at Thorndale we know that cats with chronic constipation problems can go on to develop megacolon. We recommend that cat owners monitor their cat’s bowel habits by cleaning the box daily. Sometimes with multiple cats and multiple litter boxes in a house it is extremely difficult to know who is doing (or not doing) what. If you see your cat squatting as to urinate or defecate and nothing is coming out, you need to call us at 610-873-4091. Urinary tract obstructions often look like constipation to owners. These can be life threatening in a very short time. If you are certain your cat is urinating but it is still straining in the box, your cat may be dealing with constipation and potentially a megacolon. Yep – you still need to call us.
What Exactly is Megacolon?
The colon is a tubular, muscular structure which represents the termination of the intestinal tract. It is continuous with the rectum. The colon has several functions, such as absorption of water, storage of feces, and defecation (emptying of the bowel). When the muscles in the wall of the colon are stimulated to contract by nerves from the spinal cord, fecal material is pushed out of the body.
Megacolon is a condition of colonic dilation and is a fairly common problem in the cat.
Contributing Factors
Any condition which slows movement of material through the colon or causes an obstruction in the colon may lead to constipation. Chronic constipation can lead to development of megacolon. Some possible causes would include refusal to use a soiled litterbox, impaction with hair or foreign material, injury to the spinal cord, intestinal cancer, intestinal strictures, and dehydration, often due to kidney disease or diabetes mellitus.
Prevalence
Megacolon generally occurs in middle-aged to older cats, but has also been seen in cats only 3-4 years old. Some investigators feel that it occurs more commonly in male cats than in females. It occurs in both purebred and non-purebred cats.
Causes/Transmission
If the nerves to the colon do not function properly, the muscles of the colonic wall will not contract properly. Eventually, these muscles stretch and the colon begins to enlarge. When fecal material accumulates and is not moved out of the body, severe constipation results. With time, the colon can become 3-4 times larger than in the normal cat.
As noted above, an injury to the spinal cord can result in the development of megacolon. Also, mechanical obstruction caused by tumor, foreign bodies, hairballs, and strictures can lead to megacolon. However, in most cases, we can not determine the reason that the nerves to the colon quit functioning so it is termed “idiopathic.”
Clinical Signs
Many cats with megacolon appear relatively healthy and have no signs other than chronic constipation. When other signs are present, these include a distended abdomen, anorexia, weight loss, vomiting, nausea, and straining to defecate. In severe cases, the rectum may protrude from constant straining.
Diagnosis
In many cases, the history given by the owner is suggestive of megacolon and it can be confirmed by palpation of the abdomen or examination of the rectum. It can be helpful to take an abdominal x-ray to determine the extent of the fecal retention.
Treatment
Usually, a medical approach is tried first, with surgery reserved for unresponsive cases. A medical approach involves the use of supplemental fluids, laxatives, stool softeners, colon wall stimulants, and high fiber diets. Pumpkin pie filler can be beneficial in some cats. Fiber supplements, such as unflavored Metamucil can help as well. Do not use the encapsulated forms of fiber, only powders. If the fiber capsule does not completely transit the esophagus into the stomach, it will swell as it absorbs water and can cause breathing or heart problems as it is stuck inside the esophagus in the chest cavity.
These medical treatments do not correct the underlying cause, but they will help fecal material to pass so the cat does not become constipated and ill. Intermittent enemas may be required to soften and break up fecal balls so they are easier to pass. Never use an over the counter enema in cats! Some of these can produce severe dehydration and death. Generally, enemas can be administered in our hospital without anesthesia. Occasionally, obstipated cats will need to be anesthetized and the colon manually evacuated and flushed.
The medical approach may be successful for several months or years, but will generally fail at some time. When this happens, surgery must be considered. A procedure called subtotal colectomy removes most of the non-functioning part of the colon. Although this procedure involves removal of most of the colon, the anal sphincter (valve) is left intact so the cat should not lose bowel control.
Since one of the colon’s primary responsibilities is to remove excess fluid from the fecal material, the cat that has had a subtotal colectomy will have rather soft stools immediately after surgery. In addition, there may be several bowel movements each day. However, after 1-2 months, most cats have soft, but formed, stool and will average 3 bowel movements every 2 days. There should be no loss of fecal control.
Prognosis
For cats who depend only on medical therapy, the long-term prognosis is fairly guarded. Owners must pay attention to the cat’s bowel habits. For those who undergo successful surgery, the prognosis is good.
Prevention
Owners can offer preventive measures with the following:
- Keep litter boxes clean to encourage frequent elimination
- Comb the cat (especially longhaired cats) to remove excessive hair
- Use laxatives (“hairball medication” ) as needed – see your veterinarian for recommended products.
- DO NOT use any enema products. Always leave this to veterinarians as some products are toxic to cats.