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Pet Owner Version

Disorders of the Stomach and Intestines in Cats


Alice Defarges

, DVM, DACVIM, Department of Clinical Studies, Ontario Veterinary College, University of Guelph;

Shauna Blois

, DVM, DVSc, DACVIM-SAIM, University of Guelph, Ontario Veterinary College;

Edward J. Hall

, MA, VetMB, PhD, DECVIM-CA, Langford Vets, Bristol Veterinary School;

Thomas W. G. Gibson

, BSc, BEd, DVM, DVSc, DACVSMR, Department of Clinical Studies, Ontario Veterinary College, University of Guelph;

Kelly D. Mitchell

, BSc, DVM, DVSc, DACVIM, Toronto Veterinary Emergency Clinic

Reviewed/Revised Aug 2018 | Modified Oct 2022

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)

The large intestine (also called colon or large bowel) helps maintain fluid and electrolyte (salt) balance and absorb nutrients; it also temporarily stores feces and provides an environment for healthy intestinal bacteria. When the large intestine is damaged by illness, parasites, or other causes, diarrhea is often the result.

Inflammation of the colon (called colitis) may be short- or longterm. Cats with chronic colitis tend to be middle-aged and are often purebred. In most cases, the cause is unknown; bacterial, parasitic, traumatic, kidney-related, and allergic causes are suspected. Inflammation may be the result of a defect in the function of the immune system in the colon. An exaggerated reaction to dietary or bacterial factors within the intestine, genetic predisposition, or results of previous infectious or parasitic disease have also been implicated.

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 and vomiting are uncommon.

If possible, the cause of the inflammation should be identified and eliminated. Your veterinarian will ask detailed questions about your cat's history and conduct a physical examination. Trials with specific foods can also be used to diagnose some causes of colitis. It may also be necessary to do additional testing, which may include taking blood, urine, and fecal samples; abdominal x-rays or ultrasonography; endoscopy; or biopsies.

Treatment is based on the cause of inflammation. If possible, the underlying cause should be identified and treated. Follow your veterinarian’s recommendations for diet. You may be asked to withhold food for 24 to 48 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. Your veterinarian may also recommend a 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 an antibiotic or 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. Antiparasitic medications may also be recommended.

Longterm colitis is likely to improve initially, but signs frequently recur. Most cats with inflammatory bowel disease cannot be cured and will need some form of longterm treatment.


Constipation is the infrequent or difficult passage of feces. The fecal material is often dry and hard. It 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 severe constipation with a mass of dry, hard feces that does not pass.

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 the most common cause 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. Dry, hard feces can also occur due to insufficient water intake or reluctance to defecate (for example, because of a dirty litter box, guarding of the litter box by another household cat, or painful defecation). Some cats with longterm constipation or obstipation may develop 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. Your veterinarian will feel the abdomen to see whether the colon is distended with firm feces. Abdominal x-rays and a rectal exam are often also needed. Additional tests (such as abdominal ultrasonography, colonoscopy, or blood and urine tests) may be needed to help identify the cause of constipation.

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, improving opportunities for defecation (for example, providing more litter boxes and cleaning boxes more frequently), and using appropriate laxatives (usually for a short time only). Be sure to only 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, especially among cats in close contact. It is very closely related to the virus that causes a more serious disease, feline infectious peritonitis Feline Infectious Peritonitis (FIP) Feline infectious peritonitis (often called FIP) is a severe, usually fatal disease caused by a feline coronavirus. Coronaviruses are a family of viruses that chiefly cause respiratory infections... read more . 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. Most infections cause mild signs, if any. Occassionally, severe vomiting, diarrhea, and respiratory signs (such as sneezing and coughing) can be seen.

The virus is extremely widespread in cats, and many cats that recover from the infection still harbor and shed the virus. 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. There is no specific treatment; however, affected cats should receive supportive treatment and fluids, if needed.

Inflammation of the Stomach (Gastritis)

Gastritis is sudden or longterm vomiting caused by inflammation of the stomach. It is caused by eating something that irritates or injures the stomach lining or by infections, parasites, body-wide illnesses, drugs, poisons, immune system dysfunction, or stomach tumors. In cases of short-term gastritis, the vomiting is sudden and 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 or other signs may also be present, depending on the cause. Longterm vomiting is usually intermittent and may be associated with weakness, lethargy, weight loss, dehydration, and electrolyte (salt) imbalance. Lymphocytic-plasmacytic gastritis and eosinophilic gastritis are types of longterm gastritis that involve the movement of immune cells into the tissues of the stomach.

The diagnosis is typically made by evaluating the cat's history, a physical examination, and response to treatment. Blood, urine, and fecal tests may be necessary, along with x-rays and/or an abdominal ultrasound. Visualizing the stomach with a long, flexible scope (endoscopy) and evaluating tissue samples may be necessary in cats that have longterm gastritis.

Treatment for gastritis is the same as for vomiting Feline Infectious Peritonitis (FIP) Feline infectious peritonitis (often called FIP) is a severe, usually fatal disease caused by a feline coronavirus. Coronaviruses are a family of viruses that chiefly cause respiratory infections... read more . Cats with lymphocytic-plasmacytic or eosinophilic gastritis may require medications to suppress the immune system. The outlook depends on the cause of the vomiting and the likelihood of correcting the underlying disorder.

Cancers of the Digestive System

Cancer of the digestive system is uncommon and represents less than 10% of all cancers in cats. When it does occur, it most commonly develops in the small intestine. Older animals are predisposed, occurring with an average age of 10 to 12 years in cats. Siamese cats have an increased risk for some types of intestinal cancer. 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). Lymphoma and adenocarcinoma are two common types of digestive system tumors seen in cats.

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), loss of appetite, weight loss, and lethargy are the most common signs. Constipation, straining to defecate, abdominal pain, abdominal swelling, and abdominal infection associated with the rupture of the affected bowel have also 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. Blood tests, abdominal x-rays and ultrasonography, and endoscopy may also be necessary. The diagnosis is confirmed by tissue biopsy. Treatment involves surgical removal and/or chemotherapy, depending on the type of tumor. 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. Malignant tumors usually have a poor prognosis with survival times of less than 6 months.

Gastrointestinal Obstruction

Gastrointestinal obstruction is the blockage of the digestive tract. The blockage can arise outside, within the wall, or inside the cavity of the digestive tract. An obstruction interferes with the passage of food and fluids, can damage digestive tissues, and can result in life-threatening consequences.

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 gastric or small-intestinal obstruction vary but often include vomiting and loss of appetite. Other signs include lethargy, 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. Abdominal x-rays are often necessary. Ultrasonography or examination using an endoscope may also be used to identify the problem. Blood tests are performed to identify complications from the obstruction.

Cats that have generalized signs of illness, such as depression or fever, benefit from intravenous fluid treatment. An endoscope can be used to remove some objects from the stomach. If an obstruction cannot be removed using the endoscope or if it occurs in the intestines, 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 as long as they are diagnosed and treated quickly.

Gastrointestinal Ulcers

Gastrointestinal ulcers are wounds in the stomach or intestinal lining caused by stomach acid or digestive enzymes. They are uncommon in cats. Gastrointestinal ulceration is often associated with tumors in cats, but the cause can also be unknown.

Cats with stomach ulceration may have no signs and may develop sudden, life-threatening bleeding within the digestive tract. 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. Blood tests, abdominal ultrasound scans or x-rays may be used. To confirm the diagnosis, 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. Hospitalization with intensive care is often needed because of the high risk of severe bleeding. 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. Antibiotics are also sometimes used. Your veterinarian will recommend an appropriate diet.

Ideally, ulcer healing should be monitored with endoscopy. The outlook for cats with ulcers that are not caused by malignant tumors is good. Outlook is guarded to poor for those with ulcers caused by tumors.

Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD) is actually a group of digestive system diseases that are recognized by certain persistent signs (see below) and by the presence of 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. Lymphocytic-plasmacytic enteritis and eosinophilic enteritis are the most common types in cats.

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. In cats, there is an association between inflammatory liver disease, pancreatitis, and IBD. This combination of inflammatory disorders is often referred to as triaditis. Although unproved, there may also be an association between severe IBD and intestinal tumors.

Inflammatory bowel disease can be difficult to diagnose, because many of its signs can be seen in other diseases as well. Veterinarians often use blood, urine, and fecal tests to rule out other diseases and to identify complications, such as low levels of protein or electrolytes. An abdominal ultrasound may help to identify abnormal sections of the digestive tract. Intestinal changes caused by the disease may be seen using an endoscope in some cases. Tissue biopsies obtained with an endoscope or surgery are necessary for the diagnosis of IBD.

The goals of treatment are to reduce diarrhea and vomiting, promote appetite and 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. Antiparasitic drugs, certain antibiotics, vitamin supplementation, immunosuppressants (medications to suppress the immune system), or other anti-inflammatory drugs may also be recommended.

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, food sensitivity, or food allergy. Some cats are reluctant to change foods. Talk to your veterinarian if your cat refuses to eat a recommended food. Do not force the food or allow your cat to starve. Supplementation of dietary fiber alone is rarely effective in severe cases.

The response to treatment varies, and the outlook is uncertain. 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 Exocrine Pancreatic Insufficiency The pancreas is an organ that has 2 main functions: endocrine and exocrine. The endocrine pancreas produces the hormones insulin and glucagon, which regulate blood sugar levels. The exocrine... read more , whereas most cases of absorption failure are caused by diseases in the small intestine. Examples of small-intestinal disease include inflammatory bowel disease, infectious diseases (disorders caused by viruses, bacteria, or parasites), dietary sensitivities, and intestinal tumors.

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). The cat’s history is particularly important because it may suggest a specific food allergy, consumption of non-food items, or other sensitivity. Initial tests usually include blood, urine, and fecal tests; x-rays; and an abdominal ultrasound. Specialized blood tests (such as tests for feline leukemia virus, feline immunodeficiency virus, or thyroid function) may also be necessary. The diagnosis is confirmed by taking biopsies of intestinal tissue by surgery or with an endoscope.

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. It is very important that you provide the special diet for your cat exactly as instructed by your veterinarian. Oral anti-inflammatory medication may be prescribed if the initial response to the exclusion diet is disappointing.

The outlook for malabsorption is good if there is a simple solution (such as exocrine pancreatic insufficiency). However, the outlook worsens for cats with severe disease of the small intestine.

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