Megacolon: A Terrible Outcome for Constipated Pets
November 26, 2012
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By Dr. Becker
Literally speaking, “megacolon” means large colon. It’s a condition in which too much waste accumulates and causes the bowel to enlarge well beyond its normal diameter.
Megacolon is much more common in cats than dogs. It can occur in any age, breed, or sex of cat, however, most cases are seen in middle-aged male kitties – the average age is about 5.8 years.
The colon is a part of the digestive tract that starts at the cecum and ends at the rectum. The cecum is the point where the small and large intestines meet. The main job of the colon is to temporarily store waste while extracting water and salt from it, and to move feces down to the rectum in preparation for elimination.
In megacolon, the waste doesn’t pass through to the large intestine normally. For whatever reason, the colon doesn’t release its contents.
Recent studies show that cats with megacolon seem to have a defect in the ability of the muscles of the colon to contract. This causes chronic constipation and also obstipation, which is severe, unrelenting constipation that blocks the passage of both gas and waste through the colon.
So, megacolon is a terrible condition in which the large intestine is extremely dilated, has very poor motility, and there is an accumulation of fecal material that the animal can’t eliminate from his body.
Megacolon Can Be Congenital or Acquired
Megacolon can be present at birth, or it can be an acquired condition, which is more common. Animals with congenital megacolon have a lack of normal smooth muscle function through the large intestine from birth.
Acquired megacolon results when the large intestine chronically retains feces, the water has been completely resorbed out of the colon, and the feces become really hard and solid. If these masses of waste material remain for a prolonged amount of time, the colon distends and enlarges. This can result in irreversible colon inertia, which means the colon’s smooth muscle gets so stretched out and fatigued that it no longer effectively contracts to move waste down to the rectum.
Acquired megacolon can also be the result of certain dietary factors, a foreign body in the colon, lack of exercise, and, for kitties, there can be litter box and/or behavior issues that cause them to hold in feces.
Another cause can be painful defecation due to an anal gland abscess or a stricture of the anus. There can also be a narrowed pelvic canal resulting from a fracture or tumor that can cause pain on defecation.
There can be a neurologic or neuromuscular disease that prevents the animal from getting into the posture necessary for elimination, or a neurologic condition that affects the nerves that control defecation.
Metabolic disorders resulting in low potassium levels or severe dehydration can also be a factor, as can certain types of drugs. There’s also idiopathic megacolon, which means we have no idea why it occurs. It just starts happening.
Symptoms and Diagnosis
Symptoms of megacolon include constipation, obstipation, infrequent elimination, straining to defecate followed by small amounts of loose stool, vomiting, loss of appetite and dehydration.
Megacolon is diagnosed based on the animal’s history and a physical exam. The vet will find a very hard colon upon palpation of the rectum and will find fecal impacts during a rectal exam.
In order to determine how severe the condition is and possible underlying causes, other tests are needed. These can include blood work, urinalysis, an ultrasound, X-rays with barium contrast studies, and also neurologic testing.
The treatment goal for megacolon is to clean out the large intestine and identify any underlying issues that have created or contributed to the condition. The type of treatment used will depend on the severity of the problem, how long it has existed, and the underlying cause.
Many animals need to be hospitalized for IV fluid therapy and to have the colon evacuated. This can involve anesthesia so that enemas and manual extraction of feces can be accomplished. Most kitties are in too much pain to undergo these procedures without sedation, and it’s also extremely stressful for them.
Treatment of less severe cases often involves the use of laxatives to attempt to evacuate the colon. In severe recurrent cases of megacolon that can’t be managed medically, surgery may be required, but it’s only recommended if all other attempts to manage the condition have failed.
In my practice, I use a combination of chiropractic care, acupuncture, dietary change, and bowel supplements to try to manage these conditions in a non-surgical fashion.
How to Prevent Megacolon in Your Cat
As a proactive vet, I encourage my clients to try to prevent megacolon through healthy lifestyle management. A moisture-rich, species-appropriate diet and a constant supply of fresh drinking water are very important in helping to prevent dehydration. I also recommend a good-quality pet probiotic and digestive enzymes with each meal.
In order to keep your kitty well hydrated, you can try adding a little bit of water to her food. You can also consider buying a drinking fountain designed for pets. Some cats who avoid drinking still water will happily drink moving water from a fountain.
Regular exercise is very important, as is helping your pet maintain her ideal body weight.
In multi-cat households, kitties should be provided with enough litter boxes of the right size in low traffic areas with the cat’s preferred litter to encourage normal and healthy defecation. If your cat is eliminating outside the box, it’s important to not only have him checked by your veterinarian, but also to experiment with different types of litter and litter boxes. Monitor your pet’s daily “output” by regularly scooping the boxes.
Regular brushing or combing of your cat to remove loose fur and debris can help keep things moving well through the GI tract and also prevent hairballs. There are a number of natural remedies for constipation that I always recommend trying before resorting to harsher laxatives. These include psyllium husk powder or coconut fiber added to each meal, or the addition of dark green leafy veggies or cat grass (if your cat will eat them).
Remember, never use a human laxative product on kitties, and if you are using a daily hairball remedy to keep things moving along in your kitty’s GI tract, I recommend you pick a petroleum-free product to avoid adding unnecessary toxins to your pet’s body.