Colitis in Cats

Colitis in Cats (Inflammation of Colon) Symptoms, Causes, Diagnosis And Treatments

Defining Colitis in Cats

Colitis is the medical term for inflammation of the colon, which is also referred to as the large intestine or large bowel. The colon is the lower part of the digestive tract. It includes and extends from the cecum to the rectum.

The cecum is the first part of the colon and forms a dilated pouch at the end of the small intestine. The rectum is the last part of the colon, which ends at and adjoins the anal canal.

Many things can cause the colon to become inflamed, including bacterial infection, infestation by internal parasites and a condition known as inflammatory bowel disease. Depending on the underlying cause, colitis in cats can be acute (sudden in onset), episodic (waxing and waning) or chronic (long-term).

Types of Colitis in Cats

Acute Colitis

Acute colitis is more common in dogs than in cats and typically is self-limiting. The underlying cause is rarely diagnosed, because the condition tends to resolve on its own.

The clinical signs (diarrhea with fresh blood and/or mucus, straining to defecate, and possibly constipation) tend to appear suddenly, although many cats seem to feel good and act fairly normally despite the diarrhea. Mild depression may be noticed by owners.

In many acute cases, the cat acts fine one minute, and the next appears painful or otherwise “off.” Acute colitis, which usually is caused by stress, ingestion of toxins or foreign bodies, dietary indiscretion or intolerance, internal parasites, drug administration or bacterial overload, generally lasts only a few days.

Episodic and Chronic Colitis

Episodic and chronic feline colitis are characterized by sporadic mild to severe clinical signs. Episodic cases generally last only a few weeks per episode, while chronic colitis persists for months and tends to worsen with time.

Purebred cats are prone to feline lymphocytic-plasmacytic (LPC), also called inflammatory bowel disease. The clinical signs are the same as in acute cases; they just last longer and tend not to resolve without treatment.

Chronic or episodic colitis typically are caused by an underlying medical disorder such as neoplasia, feline leukemia virus (FeLV), feline immunodeficiency virus (FIV) or some other viral or bacterial systemic or gastrointestinal infection.

Diagnosing Colitis in Cats

Initial Evaluation

A thorough history from the cat’s owner, and a complete physical examination that includes gentle palpation of the abdomen and assessment of the cat’s presenting symptoms, will be conducted in suspected cases of colitis.

Most veterinarians assessing a cat with diarrhea and signs of abdominal pain will also take blood and urine samples as part of their initial evaluation. Routine blood and urine tests usually are normal in cats with acute colitis, but they may reveal an underlying medical disorder that is contributing to cases of secondary chronic colitis.

Diagnostic Procedures

Rectal palpation and fecal examinations are among the first diagnostic tests for cats with signs of large bowel diarrhea. These may involve fecal flotation, direct fecal smear, rectal cytology, bacterial culture and/or fungal culture.

The results of rectal and fecal tests can disclose the presence of bacteria, fungi, nematodes, protozoal parasites and other infectious organisms. Abdominal imaging, including radiographs (X-rays), barium enemas and abdominal ultrasound, can help identify impactions, masses or other physical abnormalities that might be contributing to the cat’s symptoms, although abdominal ultrasound isn’t a very reliable screening tool for large bowel disease.

These imaging techniques can be time consuming, costly and inconclusive. Specialized tests for diabetes, kidney disease, hyperthyroidism, pancreatitis, feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) may also be recommended, because each of these conditions can cause or contribute to colitis or colitis-like symptoms in cats.

Colonoscopy (an endoscopic examination of the colon), with multiple biopsies of the lining of the large intestine taken from several different locations, is the diagnostic technique of choice for any sort of colon disease.

Proctoscopy (an endoscopic examination of the rectum) is also available to look at and take biopsy samples of the terminal end of the large intestine. Both of these procedures are performed under heavy sedation or general anesthesia and typically are only done in severe, chronic cases.

The biopsy samples are sent to a laboratory for microscopic assessment by a skilled veterinary pathologist, using a process called histopathology.

Acute colitis is sometimes diagnosed after-the-fact, when the cat’s sudden symptoms of large bowel diarrhea go away on their own without medical treatment, or resolve after a change in diet.

Special Notes

Surgical biopsy samples of the lining of the colon are not routinely taken by entering the abdomen directly through the abdominal wall (this is called a “laparotomy”). Open abdominal surgery increases the patient’s risk of bacterial contamination and systemic infection.

Symptoms of Colitis in Cats

Effects of Colitis – From the Cat’s Point of View

The most common symptoms of feline colitis involve changes in the consistency of the cat’s stool and increasingly frequent trips to the litter box. Affected cats typically have diarrhea, often tinged with fresh blood, and an upset tummy.

The symptoms appear suddenly if the colitis is acute, wax and wane if the colitis is episodic, and come on slowly then worsen with time if the condition is chronic. Cats can be quite stoic and may show no outward signs of abdominal pain, even when it is severe.

Symptoms of Colitis – What the Owner Sees

Owners of cats with colitis may notice some combination of the following signs:

  • Diarrhea with traces of fresh (red) blood (hematochezia)
  • Diarrhea with traces of mucus or undigested fat (slimy, greasy loose stools)
  • Straining to defecate, with or without success (tenesmus)
  • Difficult or painful evacuation of stool (dyschezia)
  • Increased frequency of defecation or attempts to defecate
  • Passage of small amounts of fecal matter
  • Increased urgency to reach the litter box

These are commonly referred to as signs of “large bowel diarrhea.” However, they also can be associated with disorders of the small intestine.

Cats with acute colitis, sometimes called “stress colitis,” usually have large bowel diarrhea and tenesmus without other signs of illness. Their stool is small in volume, semi-formed to liquid and contains mucus and bright red blood.

The first portion of stool may look fairly normal, but it becomes cloudy and jelly-like at the end. Cats with moderate to severe chronic or episodic colitis have similar symptoms, but they last for weeks to months rather than days.

In chronic cases, the cat may develop signs of malnutrition, although this is uncommon. Chronic colitis can cause one or more of the following symptoms, in addition to the signs of large bowel diarrhea:

  • Shying away from being touched
  • Hiding from people or other pets
  • Sleeping more than usual
  • Vomiting
  • Dehydration
  • Loss of appetite (inappetance, anorexia)
  • Weight loss
  • Poor hair coat
  • Poor body condition
  • Lethargy

If the small intestine, the upper part of the intestinal tract, is also inflamed, the cat may have black tarry stools, in addition to or instead of diarrhea with red blood and mucus.

Cats at Increased Risk

Acute colitis can occur in any cat but mainly is seen in young cats with internal parasites, intestinal bacterial overgrowth or dietary indiscretion. Free-roaming outdoor cats are predisposed to acute colitis.

Chronic colitis is more common in middle-aged and older cats and tends to be caused by cancer (neoplasia) or inflammatory bowel disease (IBD). Purebred cats have an increased incidence of lymphocytic-plasmacytic inflammatory bowel disease.

Causes & Preventing Colitis in Cats

Cause of Colitis in Cats

The colon, also called the large bowel or large intestine, is the last functional part of the gastrointestinal tract. It is responsible for the final stages of digestion before the digestive waste products, in the form of feces, are eliminated.

Colitis is a condition that occurs when the lining of the colon becomes irritated and inflamed, disrupting the last part of the digestive process. Inflammation of the colon triggers a cascade of gastrointestinal events on a cellular level and ultimately reduces the colon’s ability to absorb water from dietary waste products.

This causes the cat’s stool to become loose, watery, greasy and sometimes tinged with fresh red blood.

A number of things can contribute to feline colitis, which can come on suddenly (acute colitis), wax and wane (episodic colitis) or last for a long time (chronic colitis). The causes of colitis can be characterized several ways:

  1. Primary infiltrative intestinal disorders (inflammatory bowel disease, malignant neoplasia/cancer)
  2. Infectious diseases (acute infectious enteritis, internal parasites, bacterial, fungal or viral infection, infection by other microorganisms)
  3. Other primary medical diseases or disorders that cause secondary large intestinal irritation (administration of antibiotics which upset the normal flora of the bowel, food allergies, sensitivity to or intolerance of certain dietary ingredients, environmental stress, dietary indiscretion, ingestion of toxins or foreign bodies, bacterial overgrowth).

Tritrichomonas foetus has been identified as a gastrointestinal pathogen in domestic cats. This parasite can infect cats of any age, breed or gender, but it tends to show up most commonly in young cats that are housed in crowded or unsanitary conditions.

It is important for a veterinarian to figure out what is causing a cat’s irritated colon, so that an appropriate and effective treatment plan can be implemented.

Preventing Colitis in Cats

Preventing feline colitis requires a conscientious owner and consistently good overall cat care. Cats should be de-wormed in accordance with their veterinarian’s anti-parasite protocol.

Colitis is much less frequent in indoor cats than it is in cats that are allowed to roam freely outdoors. Dietary modification can help prevent recurrent episodes of colitis if food allergies are the culprit, although any changes in diet should be made gradually.

Owners should keep all medications and household cleaning products well out of their cat’s reach. Cats should also be kept away from other animals that are known to be sick, especially those that are showing signs of respiratory, gastrointestinal or other potentially contagious diseases.

Special Notes

Some of the organisms that cause colitis in domestic cats have the potential to infect people, especially people who have weak or suppressed immune systems. These organisms include:
1) bacteria (enterotoxigenic Escherichia coli, certain Salmonella species, Campylobacter and Clostridium);
2) protozoa (Tritrichomonas, Giardia);
3) helminth (worm) parasites (Trichuris), among others. “Zoonosis” is the medical term for diseases of animals that can be transmitted to humans.

Treatment of Colitis in Cats

Goals of Treating Colitis in Cats

Colitis is a complicated condition that requires an accurate diagnosis before effective treatment can begin. The therapeutic goals of treating this disorder are to relieve the cat’s pain and discomfort, restore normal bowel function, resolve large bowel diarrhea and eliminate any identifiable contributing conditions.

Treatment Options

The choice of treatment will depend on why the cat’s colon is inflamed and the frequency and severity of its symptoms. Most cats with acute colitis are treated symptomatically, because the cause of their condition is never determined and they typically get better on their own.

However, cats with chronic or episodic colitis almost always need medical attention. In some cases, colitis can actually be cured. Other times, it can only be controlled through medical management and dietary modification.

Outpatient treatment is preferred, unless the cat’s diarrhea is so severe that it becomes dangerously dehydrated and requires intravenous fluid and electrolyte replacement, which must be given in the hospital.

A number of drugs are available to treat colitis, including antibiotics, anthelmintics (anti-parasitic drugs), and other antimicrobial medications. Anti-inflammatory and immunosuppressive drugs, especially corticosteroids, are often used in severe or refractory cases. Cats given steroids should be checked by their veterinarian regularly and slowly weaned off of the drugs as soon as it is appropriate.

Oral motility modulators can firm the stool and provide relief from diarrhea. Withholding food for 24 hours can help minimize the severity of colitis, although this should only be done under a veterinarian’s supervision.

Bland food will be reintroduced in small portions – rice, low-fat cottage cheese, yogurt, tofu, strained meat baby food and boiled or broiled chicken are often recommended. Prescription diets formulated for cats with sensitive digestive tracts are available to control colitis outbreaks.

These diets are highly digestible and promote the maintenance of “good” intestinal bacteria. An elimination or hypoallergenic diet may be appropriate if food allergies are the suspected culprit.

Foods or supplements containing soluble fiber can relieve the straining and discomfort that plague cats with chronic colitis. Fatty acid supplements can soothe the irritated colon lining.

All cats should have free access to fresh water, unless a veterinarian recommends otherwise. Anxiety and stress can contribute to outbreaks of feline colitis. Cats prone to digestive irritation should be kept in a calm, quiet, safe indoor environment.

Until recently, there was no reliable treatment for Tritrichomonas foetus infections in cats. Now, veterinarians have a medication that eliminates these organisms from the cat’s system.

All prescriptions should be administered in strict accordance with the veterinarian’s instructions. If these therapies don’t resolve the cat’s colitis, colon cancer or some other disorder may be involved.


The prognosis for cats with colitis ranges from excellent to guarded. Acute colitis usually is very responsive to supportive care. Chronic allergic colitis also has a good prognosis, with appropriate dietary management.

The outlook for cats with other types of chronic or episodic colitis is more variable, depending upon the cause of their condition. If infections and parasites can be eliminated, the prognosis is good for these cats, as well.

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