Colitis is the medical term for inflammation of the colon (also called the large intestine or large bowel), which is the lower part of the gastrointestinal tract, extending from the cecum to the rectum. The cecum is the first part of the colon and forms a dilated pouch at the termination of the small intestine. The rectum is the last part of the colon, which ends at the anal canal. Colitis in cats can be acute, episodic or chronic.
Causes of Colitis in Cats
The colon is an essential part of the gastrointestinal tract and is responsible for the final stages of digestion, right before the digestive waste products (stool or feces) are eliminated. When the layers of tissue lining the large intestine become irritated and inflamed, the final phases of digestion are disrupted, causing the stool to become loose, watery, greasy and tinged with fresh blood. Colonic inflammation causes a cascade of cellular events that ultimately reduces the ability of the colon to absorb water from fecal matter, causing large bowel diarrhea and a number of other classic symptoms.
Feline colitis can be caused by a number of things, which generally are characterized as either:
1) primary infiltrative intestinal disorders (inflammatory bowel disease, malignant neoplasia/cancer); 2) infectious diseases (acute infectious enteritis, internal parasites, bacterial, fungal, viral or protozoal infection, infection by other microorganisms); or 3) other primary medical diseases or disorders that cause secondary intestinal irritation (administration of antibiotics which upset the normal bowel flora, food allergies, sensitivity to or intolerance of dietary ingredients). Recently, Tritrichomonas foetus has been identified as a gastrointestinal pathogen in companion cats. This protozoal parasite can infect cats of any age, breed or gender, but tends to occur most commonly in young cats kept in crowded and/or unsanitary conditions. Determining the underlying cause of acute, episodic or chronic colitis is critical to successful treatment.
Prevention of Feline Colitis
Preventing colitis in companion cats requires a conscientious owner with good cat care management. Cats should be de-wormed prophylactically in accordance with the attending veterinarian's anti-parasite protocol. The occurrence of colitis is much less frequent in indoor cats that are not free-roaming. Dietary modification and management may help prevent recurrent episodes of colitis in predisposed animals. Owners should avoid making abrupt changes in their cat's diet and should keep all medications and household cleaning products well out of their reach. Companion cats should be kept away from other cats that are known to be sick or are showing signs of respiratory, gastrointestinal or other potentially contagious illness.
Some of the organisms that cause colitis in domestic cats have the potential to infect people, especially those whose immune systems are weakened or suppressed. These include: 1) some bacterial microorganisms (enterotoxigenic Escherichia coli, certain Salmonella species, Campylobacte and Clostridium); 2) some protozoal organisms (Tritrichomonas, Giardia); and 3) some helminth (worm) parasites (Trichuris), among others. "Zoonosis" is the medical term for diseases of animals that may be transmissible to humans.
Colitis refers to inflammation of the colon, which also is called the large intestine or the large bowel and is the lower end of the gastrointestinal tract. There are a number of different types of colitis, each of which has different causes but similar clinical signs. One of the most common signs of colitis in cats is a change in the consistency of stool. Colitis in cats can be acute or chronic, and it can also wax and wane with time.
Symptoms of Feline Colitis
Cats with colitis tend to have some combination of the following symptoms:
Diarrhea with traces of fresh (red) blood (hematochezia)
Diarrhea with traces of mucus or undigested fat (slimy or greasy diarrhea)
Straining to defecate (tenesmus), with or without success
Difficult or painful evacuation of stool from the rectum (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, one or more of these symptoms can be associated with disorders that affect both the large and small intestines.
Cats with acute colitis, sometimes referred to as "stress colitis," usually have large bowel diarrhea and tenesmus without signs of systemic illness. The diarrhea in acute cases is usually small in volume, semi-formed to liquid and contains mucus and bright red blood. In many cases, the first portion of stool looks somewhat normal but the bowel movement becomes cloudy and jelly-like at the end. Cats can be quite stoic. They may show no outward signs of abdominal pain, even when their condition comes on suddenly and severely. Nonetheless, colitis typically is extremely painful.
Cats with moderate to severe chronic or episodic colitis have virtually identical symptoms, but they persist for weeks instead of days. In chronic cases, the animal can also develop systemic signs of malnutrition due to malabsorption of dietary nutrients, although this is uncommon in domestic cats. 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
Loss of appetite (inappetance, anorexia)
Weight loss (uncommon)
Poor hair coat
Poor body condition
If the upper part of the intestinal tract – called the small intestine or small bowel - is also involved, the cat may have black tarry stools, in addition to or instead of diarrhea with traces of fresh blood and mucus.
Cats at Increased Risk
Acute colitis can occur in any cat but predominantly is seen in young cats with intestinal parasites, gastrointestinal bacterial overgrowth or dietary indiscretion. Free-roaming outdoor cats are predisposed to developing acute colitis. Chronic colitis is more common in middle-aged and older cats and tends to be caused by malignant neoplasia (cancer) or inflammatory bowel disease (IBD). Purebred cats are predisposed to developing a particular type of IBD called lymphocytic-plasmacytic IBD.
Diagnosing the cause of colitis in cats is not an easy task. It requires a diligent and methodical course of inquiries and diagnostic tests.
Diagnosing Feline Colitis
A thorough history and physical examination, including careful abdominal palpation and assessment of the cat's presenting symptoms, should be conducted in all suspected cases of colitis. Among the first diagnostic tests for cats with either acute or chronic colitis are rectal and fecal examinations, which may involve fecal flotation, direct fecal smear, rectal cytology, bacterial culture and/or fungal culture. These tests can disclose the presence of infectious intestinal microorganisms such as bacteria, fungi, nematodes and/or protozoal parasites, among others. Routine blood and urine assessments typically are normal in acute cases but may reveal a primary underlying medical disorder contributing to secondary chronic colitis.
Abdominal imaging (radiographs [X-rays], barium enemas and abdominal ultrasound) can help identify impactions, masses or other possible contributing causes, although abdominal ultrasound is a poor screening tool for large intestinal disease. These imaging techniques are time consuming, expensive and often not diagnostically conclusive. Specialized tests for diabetes, renal (kidney) disease, hyperthyroidism, pancreatitis, feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) may also be performed, because these conditions can cause colitis or colitis-like symptoms in cats.
Colonoscopy (endoscopic examination of the colon), with multiple biopsies of the lining of the lower bowel taken from multiple locations, is the diagnostic technique of choice for infiltrative colonic disease. Proctoscopy (endoscopic examination of the rectum) is also available to visualize and biopsy the terminal end of the large intestine. These procedures are performed under heavy sedation or general anesthesia and typically are only done in severe, chronic cases. Biopsy samples will be sent to a laboratory for microscopic assessment by a process called histopathology.
Acute colitis sometimes is diagnosed based simply on the rapid resolution of the cat's symptoms without medical treatment, or alternatively on the cat's response to dietary modification and management.
Biopsy samples of the colon are not routinely taken by laparotomy (surgically entry into the abdomen through the abdominal wall), because of the increased risk of bacterial contamination and infection associated with that procedure.
Colitis is a complicated condition that requires an accurate diagnosis before effective treatment can begin. The therapeutic goals for treating colitis are to relieve the cat's physical symptoms and remove or resolve any identifiable underlying conditions. The choice of treatment will depend upon why the cat's colon is inflamed and the frequency and severity of its symptoms. In some cases, colitis can actually be cured, while in others it can be controlled through medical management and dietary modification. Outpatient treatment is preferred, unless the accompanying diarrhea is so severe that the cat becomes dangerously dehydrated and requires inpatient intravenous fluid and electrolyte replacement therapy.
Treatment Options for Cats with Colitis
Most cases of acute colitis in cats are treated symptomatically, because the cause is never determined and the symptoms typically resolve on their own. However, chronic colitis almost always requires further medical attention. A number of drugs can be used to treat feline colitis, depending upon its specific cause. Antibiotics, anthelmintics (anti-parasitic drugs), antiprotozoal medications and other antimicrobial drugs are available to treat infections by ringworm, whipworm, tapeworm, hookworm, giardia, clostridia, salmonella, campylobacter and other microorganisms. Anti-inflammatory and immunosuppressive drugs, including corticosteroids, often are used in particularly severe or refractory chronic cases. Cats given steroids require regular veterinary re-checks to properly manage the treatment. So-called "motility modulators" can provide symptomatic relief from the consequences of chronic large bowel diarrhea caused by colitis.
Cats should be monitored closely no matter what medications are given. Any prescriptions should be administered in strict accordance with the veterinarian's instructions and should be given for the full duration of the prescribed time. New drugs and other treatments are constantly under development. Until fairly recently, there was no available treatment for Tritrichomonas foetus infection in cats. Veterinarians now have a medication that effectively resolves the diarrhea and other symptoms of colitis caused by this organism and eliminates the organism from the cat's system.
Withholding food for 24 to 36 hours can help minimize the severity of colitis. When feeding recommences, the diet should be fed frequently in small portions and be bland – rice, low-cottage cheese, yoghurt, tofu, strained meat baby food and sometimes chicken are often recommended by veterinarians. Specific prescription diets formulated for affected felines are available to control episodic colitis outbreaks. These formulas are highly digestible and promote maintenance of "good" intestinal bacteria, while discouraging "bad" bacterial populations from thriving. An elimination or hypoallergenic diet may also be suggested, if food allergies are among the suspected causative culprits. Foods with moderate soluble fiber, and soluble fiber supplementation, can help reduce uncomfortable straining during defecation and facilitate repair of inflamed intestinal tissue. Fatty acid supplements can also help minimize the consequences of intestinal irritation. Of course, cats should always have free access to fresh water, unless a veterinarian recommends otherwise. Anxiety and stress can contribute greatly to outbreaks of colitis in cats. Cats prone to gastrointestinal irritation should be kept in a calm, quiet, stable indoor environment.
If these therapies do not resolve the cat's colitis, colon cancer or some other systemic disorder may be present. Many local colonic tumors can be removed surgically. Other cancers may be treated with radiation and/or multi-drug chemotherapy.
The prognosis for cats with colitis ranges from guarded to excellent. Acute colitis usually is very responsive to supportive care. Dietary-responsive chronic colitis carries an excellent prognosis, with appropriate dietary management. The prognosis for cats with chronic colitis is highly variable, depending upon the underlying cause of the condition. If infectious or parasitic causes can be eliminated, the prognosis is excellent for these cats, as well.