Megacolon in Cats: Symptoms, Causes and Treatment

This digestive disorder is chronic and causes great discomfort in cats. In this article, we'll tell you all about it and how to prevent it.
Megacolon in Cats: Symptoms, Causes and Treatment

Last update: 04 March, 2022

The media often tell us how we should look after ourselves to improve our digestive health. As you can imagine, this isn’t only reserved for humans. Any other animal can suffer serious consequences if it has digestive problems, and, in this article, we’re going to talk about megacolon in cats.

Here you’ll find information about this disorder, its causes, symptoms, and treatment. Don’t miss this article, because megacolon usually appears secondary to existing problems and needs professional veterinary care. Let’s get started.

What is megacolon in cats?

The term megacolon refers to a severe and irreversible dilatation of the colon. When this widening occurs, the feces are retained and motility is reduced or annulled, so that the cat isn’t able to evacuate.

The total duration of the digestive process in a cat is 12-24 hours, depending on the individual.

This ailment, if not treated, follows a progressive course which can even be fatal. This evolution begins with the retention of feces. When these remain lodged in the colon for a prolonged period of time, the walls of the colon begin to absorb their water, drying them out and making defecation difficult. As the feces accumulate, the colon dilates, leading to megacolon in cats.

Symptoms of megacolon in cats

There are several signs to show that a cat has digestive problems. In the case of megacolon, you can observe the following:

  • Painful defecation: the cat cries when going to the litter box
  • Frequent and unsuccessful attempts to defecate
  • Prolonged constipation
  • Feces outside the litter box
  • Excessive salivation
  • Vomiting
  • Dehydration
  • Bloody mucus in the stool – due to irritation of the wall of the descending colon
  • Hard tubular mass along the abdomen, perceptible by palpation

While this tubular mass is characteristic of chronic constipation and megacolon, you may have noticed that the rest of the symptoms could correspond to any digestive disorder. Therefore, if you see any of these signs, you should go to see the vet without fail.

What causes megacolon in cats?

Although constipation seems to be the main cause of megacolon in cats, the truth is that this stool retention can also be secondary to other disorders. Below is a list of the original causes of this condition:

  • Idiopathic: About 62% of cases of megacolon are idiopathic, i.e. no apparent cause is found for its origin. It’s usually attributed to a nervous degeneration of the smooth muscle of the colon, which prevents correct peristaltic movements and causes constipation.
  • Mechanical obstruction: A hip fracture, for example, can put pressure on the colon if it isn’t well aligned in the healing process. Other causes are tumors, perineal hernias, or spinal injuries, such as cauda equina.
  • Neurological damage: As the motility of the colon depends on nerve impulses, it’s logical to encounter problems in this regard with disorders such as trauma to the sacrococcygeal area. Generally, any damage to the pelvic or hypogastric nerve will cause constipation due to decreased motility.
  • Congenital megacolon: When cats turn up at the vet’s with severe constipation, it’s usually caused by a birth malformation that has caused megacolon, such as anorectal agenesis.
  • Drugs: Diuretics, antihistamines, anticholinergics and other drugs have constipation as a side effect. If constipation isn’t treated, there’s a risk of megacolon in cats.
  • Endocrine processes: Although rare, disorders such as hyperthyroidism or hypercalcemia increase water absorption, so there’s a risk of hardening of the stool, and, therefore, constipation.


Since it’s a chronic disease, the treatment of megacolon in cats must combine drugs with a change in the animal’s lifestyle and diet. Thus, the measures to be taken are as follows:

  • Diet against constipation: The water content of the cat’s food should be increased. This can be done by using wet food, cat soups, or by adding water to dry diets.
  • Insoluble fiber supplementation: This measure must be approved by a veterinarian, as this type of fiber, even though it helps to lubricate the feces, also makes them increase in size, which is a danger for an already dilated colon.
  • Pharmacological treatment: The most commonly prescribed medications are laxatives and prokinetics. The use of enemas also facilitates evacuation at specific times.
  • Surgery: In the most severe cases it’s necessary to anesthetize the animal and remove the feces manually. This can be done through an incision in the abdominal wall or through the rectum. In the worst case scenario, a subtotal colectomy, which consists of the removal of most of the colon, will be necessary.

As you can see, megacolon in cats can create major complications in the animal’s life. However, and as long as the cause is visible, you can prevent it by going to see the veterinarian at the slightest sign of chronic constipation, so don’t hesitate to get help!

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

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  • Sugiyama, T., & Davies, H. M. (2022). Megacolon. In Comparative Veterinary Anatomy (pp. 316-324). Academic Press.
  • Grossman, R. M., Sumner, J. P., Lopez, D. J., Dornbusch, J. A., Singh, A., Lux, C. N., … & Pitt, K. A. (2021). Evaluation of outcomes following subtotal colectomy for the treatment of idiopathic megacolon in cats. Journal of the American Veterinary Medical Association259(11), 1292-1299.
  • Thanaboonnipat, C., Kumjumroon, K., Boonkwang, K., Tangsutthichai, N., Sukserm, W., & Choisunirachon, N. (2021). Radiographic lumbosacral vertebral abnormalities and constipation in cats, Veterinary World, 14 (2): 492-498. Abstract.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.