Megacolon in cats is a serious condition that can lead to a life-threatening situation if left untreated. The most common causes of megacolon are idiopathic, which means the medical reason is unknown. Medical therapy is often recommended initially but there are surgical options for those cats that do not respond to medical therapy. It is important to seek veterinary care if you think your cat may have megacolon.
What is megacolon?
Hypomotility and persistent gross dilation of the colon are characteristics of megacolon in cats. Megacolon manifests as chronic constipation/obstipation that does not respond to therapy or is incurable. Cats of any age, breed, or sex can develop constipation and subsequent megacolon. The majority of cases occur in middle-aged cats (6 years on average). Approximately 3/4 of all cats that develop megacolon are male.
What causes megacolon in cats?
The 3 most common causes of megacolon in cats are idiopathic, narrowing of the pelvic canal, and neurological disease. Studies performed on cats with idiopathic megacolon have revealed a generalized dysfunction of colonic smooth muscle. Idiopathic megacolon is the most common cause of megacolon in cats, accompanying 60% of all cases.
What are the symptoms of megacolon in cats?
Clinical symptoms include reduced or painful defecation (bowel movements), and numerous unproductive attempts to defecate. Cats with megacolon often experience progressive weight loss as a result of the disease. If your cat is passing small, firm feces, there may be blood on the stool as a result of colonic irritation.
If your cat is experiencing symptoms of megacolon, it is important to take them to the veterinarian for a diagnosis. Megacolon can be a life-threatening condition if left untreated, so early diagnosis and treatment are essential.
How is megacolon diagnosed?
Megacolon is diagnosed in cats through a variety of methods. The first step in obtaining a correct diagnosis is a detailed physical examination. Your veterinarian will be able to palpate the colon and appreciate any changes that are present. Your veterinarian will likely then recommend x-rays which helps your veterinarian see the extent of the dilation in the colon.
Blood testing should also be performed as hypokalemia (low potassium) and hypercalcemia (elevated calcium) can contribute to constipation and should be addressed. In kittens that are diagnosed with megacolon, thyroid testing should be performed as congenital hypothyroidism, although rare in cats, can cause megacolon.
A colonoscopy may be recommended in some cases as this will allow your veterinarian to directly visualize the colon. A biopsy may also be performed during a colonoscopy to rule out any other possible causes of megacolon such as masses, strictures, or inflammatory lesions.
Treatment of megacolon in cats
The goal of treatment is to relieve constipation and return the cat to normal defecation. Treatment options vary depending on the cause of megacolon. If the megacolon is idiopathic, medical therapy is typically recommended. It is very important to encourage cats with megacolon to consume more water as this will reduce fecal bulk and constipation. Water fountains and canned food can be used to encourage cat water consumption in cats suffering from constipation. In some cases of constipation, weight management may prove beneficial since obesity plays a role.
In the past, it was recommended that cats with megacolon be fed diets that are rich in fiber. While fiber supplementation is beneficial for cats with constipation, it can be very problematic for cats with megacolon. By using fiber and creating fecal bulk, the stool will expand to the diameter of the already distended colon, therefore making the problem worse. The best diets to use as gastrointestinal, low-residue diets as they are highly digestible and do not contribute to fecal bulk.
Veterinarians will also recommend medications to stimulate intestinal contractions. For cases of idiopathic megacolon, cats can be treated with prokinetic medications as maintenance therapy, possibly preventing the development of megacolon. Common medications that are used are cisapride and ranitidine as they both stimulate colonic motility.
Treatment with surgery may be used to relieve severe megacolon, as well as chronic constipation that has been unsuccessful in responding to medical therapy. A total or subtotal colectomy can be performed. With the subtotal colectomy procedure, 2-3cm of the distal colon is preserved and this approach is the current recommended surgical procedure.
What is the prognosis for cats with megacolon?
For some cats with megacolon, long-term medical therapy may be sufficient but is uncommon to be successful with medical management alone. Cats who have undergone subtotal colectomy, however, will likely have a positive outcome in the long term as the surgery has a 90% success rate. However, there can be complications that lead to diarrhea, increased frequency of defecation, and tenesmus (straining to defecate) in the months after surgery. Fecal continence is not affected by this complication however some patients may experience constipation again.
In this article, we discussed megacolon in cats, its causes, treatment, and prevention. We also looked at the prognosis for cats with megacolon and what complications they may experience. Megacolon is a serious condition in cats that can lead to a life-threatening situation if left untreated. Treatment options vary depending on the cause of megacolon but typically include medical therapy and surgery. Cats with megacolon should consume more water to reduce fecal bulk and constipation. If you have any questions about megacolon in cats, please contact your veterinarian.