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Disorders of the Stomach and Intestines in Cats

By Dana G. Allen, DVM, MSc, DACVIM, Department of Clinical Studies, Ontario Veterinary College
Sharon Campbell, DVM, MS, DACVIM, Manager, Pharmacovigilance Regulatory Affairs, Veterinary Medicine Research and Development, Pfizer Inc.
Ben H. Colmery, DVM, DAVDC,
James G. Fox, DVM, MS, DACLAM, Professor and Director, Division of Comparative Medicine, Massachusetts Institute of Technology
Carlton L. Gyles, DVM, PhD, Professor Emeritus, Department of Pathobiology, Ontario Veterinary College, University of Guelph
Walter Ingwersen, DVM, DVSc, DACVIM, Specialist, Companion Animals, Boehringer Ingelheim (Canada) Ltd, Vetmedica
Lisa E. Moore, DVM, DACVIM,
Sofie Muylle, DVM, PhD, Faculty of Veterinary Medicine, Department of Morphology, Ghent University
Sharon Patton, MS, PhD, Professor of Parasitology, Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee
Andrew S. Peregrine, BVMS, PhD, DVM, DEVPC, DACVM, Associate Professor, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
Stanley I. Rubin, DVM, MS, DACVIM, Clinical Professor, Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois at Urbana-Champaign
H. Carolien Rutgers, DVM, MS, DACVIM, DECVIM-CA, DSAM, MRCVS, Senior Lecturer, The Royal Veterinary College, University of London
Jörg M. Steiner, DrMedVet, PhD, DACVIM, DECVIM-CA, AGAF, Associate Professor and Director, Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A & M University
Thomas W. Swerczek, DVM, PhD, Professor, Department of Veterinary Science, University of Kentucky

Also see professional content regarding stomach and intestinal disorders in cats.

Diseases that affect the stomach and intestines include infectious diseases such as bacterial, viral, and parasitic diseases and noninfectious disorders such as tumors and obstruction.

Inflammation of the Large Intestine (Colitis)

When the large intestine (also called colon or large bowel) is damaged by illness, parasites, or other causes, diarrhea is often the result. Cats with inflammation of the colon have a history of straining to defecate and frequent passage of mucus-laden feces, sometimes containing bright red blood. Feces are often of a small volume and a more liquid consistency. Weight loss is uncommon, and vomiting is seen in about 30% of cases.

If possible, the cause of the inflammation should be identified and eliminated. Follow your veterinarian’s recommendations for diet. You may be asked to withhold food for 24 hours to rest the cat’s digestive system. Once feeding is resumed, soluble fiber is often added to the diet. Over time, the fiber dose can be often be reduced or eliminated. When feeding is first resumed, you may be advised to provide food with a protein source that your cat has not previously eaten, such as mutton, lamb, venison, or rabbit. This is to identify any food allergies your cat may have. Cats with some types of inflammation may respond to dietary management alone (such as changing to lamb and rice, or a commercially available diet). To help the signs improve more rapidly, your veterinarian may add anti-inflammatory medication to the change in diet. Some animals require additional short-term use of medication to thicken the feces until inflammation is brought under control.


Constipation is a common problem in cats. In most instances, the problem is easily corrected. However, in cats with more serious illness, accompanying signs can be severe. The longer feces remain in the colon, the drier, harder, and more difficult to pass they become. Obstipation is constipation that resists treatment.

Longterm constipation may be due to an obstruction inside the intestines, constriction from outside the intestines, or neuromuscular problems with the colon itself. Obstruction is most common and is due to the cat’s inability to pass poorly digestible, often firm matter (such as hair, bones, or litter) that has become mixed with fecal material. Some cats with longterm constipation or obstipation may have megacolon, an enlarged intestine caused by a defect in the muscle strength of the colon. The cause of megacolon often remains undiagnosed. Some drugs cause constipation as a side effect.

Signs of constipation include straining to defecate and the passage of firm, dry feces. Some animals are quite ill and also have lethargy, depression, loss of appetite, vomiting, and abdominal discomfort. A visit to the veterinarian is advised. During the visit, be sure to tell your veterinarian if your cat has any tendency to eat bones, litter, or other hard matter.

Affected cats should receive plenty of water. Mild constipation can often be treated by switching to a high-fiber diet, keeping your cat from eating bones or other objects, providing ready access to water, and using appropriate laxatives (usually for a short time only). Be sure to provide your cat with the laxative prescribed by your veterinarian. Laxatives formulated for human use can be very dangerous for pets. In more severe cases of constipation, a veterinarian will need to remove retained feces using enemas or manual extraction while your pet is under general anesthesia. Cats with chronic constipation or megacolon that have been unresponsive to medical treatment may respond to removal of the affected section of the large intestine.

Feline Enteric Coronavirus

Feline enteric coronavirus is highly contagious among cats in close contact. It is very closely related to the virus that causes a more serious disease, feline infectious peritonitis. Infection with feline enteric coronavirus causes inflammation of the small intestine, but is not usually fatal.

The virus is shed in the feces of infected cats. Close contact between cats is required for transmission, although the possibility of transmission by contaminated objects also exists. In catteries, the virus may be a cause of mild to severe intestinal inflammation in kittens 6 to 12 weeks old. Recently weaned kittens may have fever, vomiting, and diarrhea lasting 2 to 5 days. More severely affected kittens may be unwilling to eat for 1 to 3 days. Adult cats often show no signs when infected.

The virus is extremely widespread in cats, and many cats that recover from the infection remain carriers. Enteric coronavirus infection can be prevented only by minimizing exposure to infected cats and their feces. Most cats develop an effective immune response after exposure and will recover from infection. Cats with the intestinal form of the disease do not develop signs of feline infectious peritonitis. However, if signs of disease develop in cats with feline infectious peritonitis, the disease is fatal. There is no specific treatment; however, affected cats should receive supportive treatment and fluids, if needed.

Inflammation of the Stomach (Gastritis )

Gastritis, or inflammation of the stomach, is often caused by eating something that injures the stomach lining. Vomiting is the usual sign of gastritis. In cases of short-term gastritis, the vomited material may contain evidence of whatever the cat has eaten (such as grass). Bile, froth, fresh blood, or digested blood that looks like coffee grounds may be seen. Diarrhea may also be present. Short-term or occasional vomiting is generally not associated with other abnormalities. Longterm vomiting, however, may be associated with weakness, lethargy, weight loss, dehydration, and electrolyte (salt) imbalance. The outlook depends on the cause of the vomiting and the likelihood of correcting the underlying disorder (See also Vomiting in Cats).

Cancers of the Digestive System

Cancer of the digestive system is uncommon and represents less than 1% of all cancers in cats. When it does occur, it most commonly develops in the small intestine. Older animals are predisposed. No specific cause has been identified for most intestinal tumors, although alimentary lymphoma in cats is believed to be caused by the feline leukemia virus, even in cats that test negative for the virus. Intestinal tumors in cats tend to spread rapidly and are usually malignant (cancerous).

Signs of a possible tumor vary depending on the location and extent of the tumor and associated consequences. Vomiting (sometimes with blood), diarrhea (also with blood), weight loss, constipation, straining to defecate, abdominal pain, abdominal swelling, and abdominal infection associated with the rupture of the affected bowel have been reported. Cats with intestinal tumors may also have signs of anemia, such as pale gums.

Diagnosis is based on a complete history and physical examination and confirmed by tissue biopsy. Surgical removal is the preferred treatment. Your veterinarian will also attempt to determine the extent of spread of the cancer. The outlook can vary from excellent to poor, depending on the specific type of tumor and whether all of it can be removed.

Gastrointestinal Obstruction

Obstruction of food movement out of the stomach can result from tumors, foreign objects, polyps, and overgrowth of stomach tissue.

Intestinal obstruction may be partial or complete and may be caused by foreign objects, intussusception (a condition in which the intestine telescopes on itself), incarceration (such as being constricted in a hernia), and tumors. Long, thin foreign objects (such as string, yarn, or fabric) may become attached at the base of the tongue. If the object is long enough to trail into the intestines, normal intestinal movement tends to cause a sawing or cutting motion on the gut, leading to intestinal perforation and abdominal infection.

Signs of small-intestinal obstruction may include lethargy, poor appetite, vomiting, diarrhea, abdominal pain or swelling, fever or subnormal body temperature, dehydration, and shock. To make a diagnosis, your veterinarian will need to know as much as possible about your cat’s eating habits. Access to string or sewing needles or missing objects (such as toys) may be important facts and should be reported. Abdominal palpation (gently using the hands to feel the internal organs) can allow your veterinarian to detect organ enlargement, thickened bowel loops, and gas. X-rays, ultrasonography, or examination using an endoscope may be used to identify the problem.

Cats that have generalized signs of illness, such as depression or fever, benefit from intravenous fluid treatment. If an obstruction is found and cannot be removed using the endoscope, then surgery will be needed. Cats with sudden abdominal signs of unknown cause, and those that continue to worsen, may also require surgery. Many of these animals recover well.

Gastrointestinal Ulcers

Gastrointestinal ulcers are wounds in the stomach or intestinal lining caused by stomach acid or digestive enzymes. Factors that may lead to formation of ulcers include certain drugs, tumors, infections, or generalized diseases.

Cats with stomach ulceration may have no signs. In other cases, they can have a history that includes vomiting, sometimes with blood, and abdominal discomfort that may appear less severe after a meal. Dark, tarry stools, which indicate the presence of blood, and pale gums suggesting anemia may be present. Signs may also be related to the cause of the ulcer (for example, signs related to kidney failure).

In cats that have a history of vomiting, abdominal discomfort, loss of appetite, or unexplained weight loss, there are several tests that might be performed by your veterinarian in an attempt to diagnose the cause. Abdominal ultrasound scans or x-rays may be used to confirm the diagnosis. In cases in which the cause is unclear or in those with apparent gastrointestinal disease, endoscopy and biopsy of the stomach and intestines are often recommended.

The goal of ulcer management is to determine the cause of the ulceration and then eliminate or control it. Providing supportive care is also critical. Medication directed at the ulcer itself reduces stomach acidity, prevents further destruction of the stomach lining, and promotes ulcer healing. In general, treatment should be continued for 6 to 8 weeks. Dietary management should include the use of bland diets (for example, cottage cheese and rice or chicken and rice).

Ideally, ulcer healing should be monitored with endoscopy. If the ulcers do not respond to basic medical management, a biopsy of the stomach and small intestine are the next steps. The outlook for cats with peptic ulcers and benign stomach tumors is good. Outlook is poor for those with ulcers associated with kidney or liver failure and for cats with gastric carcinoma or gastrinoma.

Inflammatory Bowel Disease

Idiopathic inflammatory bowel disease is actually a group of digestive system diseases that are recognized by certain persistent signs and by inflammation without a known cause. The various forms of inflammatory bowel disease are classified by their location in the body and the type of cell that is involved.

Inflammatory bowel disease appears to affect all ages, sexes, and breeds, although it may be more common in purebred cats. The average age reported for the development of disease in cats is 7 years. Signs are often longterm and sometimes come and go. Vomiting, diarrhea, changes in appetite, and weight loss may be seen. Inflammatory bowel disease can be difficult to diagnose, because many of its signs can be seen in other diseases as well.

The goals of treatment are to reduce diarrhea, promote weight gain, and decrease intestinal inflammation. If a cause can be identified (such as diet, parasites, bacterial overgrowth, or drug reaction), it should be eliminated. Modifying the diet, without other treatment, may be effective in some cases. In other cases, changes in diet can enhance medical treatment, allowing for the drug dosage to be reduced or for the drug to be discontinued once signs improve. Glucocorticoids, which suppress the immune system, are among the drugs most often used in the management of inflammatory bowel disease.

Your veterinarian may recommend feeding your cat a hypoallergenic or elimination diet. This means feeding a source of protein that the cat has not previously eaten. Diets with these ingredients are usually available from veterinary clinics rather than commercial outlets, or they can be home-made. This diet should be the sole source of food for a minimum of 4 to 6 weeks, and no treats of any kind should be fed unless approved by your veterinarian. These types of diets are effective in controlling signs in some cats with inflammatory bowel disease, but not in cats with food sensitivity or food allergy. Supplementation of dietary fiber alone is rarely effective in severe cases.

Although feline inflammatory bowel disease can often be controlled with an appropriate combination of diet and medication, the condition is rarely cured. Relapses may occur.


Malabsorption is poor absorption of a nutrient resulting from interference with its digestion, absorption, or both. Interference with digestion in cats is typically due to lack of certain enzymes from the pancreas, called pancreatic insufficiency (see Disorders of the Pancreas in Cats : Exocrine Pancreatic Insufficiency), whereas most cases of absorption failure are caused by diseases in the small intestine.

The signs of malabsorption are mainly due to lack of nutrient uptake and loss of nutrients in the feces. Signs typically include longterm diarrhea, weight loss, and altered appetite (loss of appetite or excessive eating). However, diarrhea may be absent even when disease is severe. Weight loss may be substantial despite a good appetite. Cats with malabsorption usually appear healthy in other respects unless there is severe inflammation or cancer. Nonspecific signs may include dehydration, anemia, and accumulation of fluid in the abdomen or other tissues. Your veterinarian may be able to detect thickened bowel loops or enlarged abdominal lymph nodes.

Diagnosing malabsorption can be complex, because longterm diarrhea and weight loss are signs that are common in several diseases. A thorough examination with appropriate laboratory tests can help determine whether the signs are caused by an underlying multisystem or metabolic disease (such as hyperthyroidism).

Treatment of malabsorption involves dietary treatment, management of complications, and treatment of the cause (if it can be identified). Dietary modification is an important aspect of the management of malabsorption. Diets generally contain moderate levels of limited protein sources, highly digestible carbohydrates, and moderate levels of fat (to reduce fatty diarrhea). Cats with inflammatory bowel disease have a higher incidence of dietary sensitivity than dogs. Your veterinarian may recommend feeding your cat an exclusion diet consisting of a single novel protein source (lamb or venison, for example) as a test when dietary sensitivity is suspected. Oral anti-inflammatory medication may be prescribed if the initial response to the exclusion diet is disappointing.

For More Information

Also see professional content regarding stomach and intestinal disorders in cats.