Inflammatory bowel disease is a condition in which inflammatory cells penetrate the wall of the intestine, causing the gastrointestinal (GI) tract to become inflamed (irritated and swollen) and interfering with important digestive and immune functions of the gut. Feline IBD is a common disorder, particularly in older cats and those with certain genetic predispositions.

Inflammation causes thickening of the mucosal lining of the GI tract, and that thickening hampers the normal digestion of food and interferes with nutrient absorption. Despite the name, inflammatory bowel disease can involve inflammation in any portion of the GI tract, from the stomach to the large intestine. Left untreated, chronic inflammation can lead to even more severe conditions, such as feline gastrointestinal lymphoma.

Inflammatory bowel disease is sometimes confused with irritable bowel syndrome (IBS), a term reserved for gastrointestinal disorders in human patients. You may also hear the term “stress colitis,” which is used to describe acute (sudden, short-term) disturbances of the colon caused by stress.

Although IBS and “stress colitis” share some of the outward signs of IBD (symptoms like diarrhea and vomiting), intestinal biopsies of patients with IBS and “stress colitis” fail to show inflammation.

Colitis literally means “colon inflammation,” which is confirmed by the finding of excess inflammatory cells within the colon walls. In IBD, inflammatory cells infiltrate the intestinal wall, leading to inflammation of the colon (colitis), the small intestine (enteritis), or the stomach (gastritis).

Your veterinarian (DVM) may also use the term chronic enteropathy, which is a broader category encompassing all chronic issues related to the GI tract of pets.

While the symptoms of IBD depend on the location and severity of the inflammation, these are the most common clinical signs in cats:

• Frequent vomiting

• Chronic diarrhea

• Blood in the stool

• Weight loss

• Decreased appetite

• Lethargy

• Mucus in the stool

• Bloating

• Straining in the litterbox

IBD can cause pain, such as abdominal cramping from diarrhea. However, a cat with IBD is more likely to experience discomfort rather than severe pain. For example, in some cases of IBD, cats may vomit hairballs because an inflamed digestive tract can’t move material along properly.

A cat who uncharacteristically protests when picked up may have abdominal pain. Keep an eye out for this kind of behavior, and contact your veterinarian if you ever suspect your cat is in pain.

The symptoms associated with IBD all have multiple potential causes, so figuring out the right diagnosis for your cat may take some time. Your veterinarian will typically use some of the following tests to narrow down the list of possible causes of your cat’s symptoms:

• Bloodwork

• Vitamin B12 testing

• Pancreatic tests (e.g., lipase test, trypsin-like immunoreactivity test)

• Fecal exam

• Parasite screening

• Diet trial

• Imaging (e.g., x-rays, ultrasound)

• Biopsy (via endoscope)

• Abdominal exploratory surgery (in rare cases)

These tests will allow your veterinarian to rule out a number of potential causes of inflammation, such as intestinal parasites, cancer, food sensitivities or food allergies, ingestion of toxins, foreign body obstructions, and disorders of the liver, pancreas, thyroid, or kidneys.

An official diagnosis of IBD can only be made via biopsy (taking a sample of tissue from the affected part of the GI tract), but cats are often treated for IBD without an official diagnosis. Your cat may get a “provisional diagnosis” of IBD, meaning that based on the available information, your veterinarian believes IBD is the most likely explanation for your cat’s symptoms.

But because so many conditions can cause IBD-like symptoms, sometimes cats are diagnosed with IBD when they in fact have a food intolerance, a thyroid disorder (like hyperthyroidism), or intestinal lymphoma (cancer). Additionally, like some humans, some cats may start out with IBD and later develop intestinal lymphoma.

Scientists and veterinarians are still figuring out the exact cause(s) of IBD, which is complicated by the fact that there are many contributors of gut inflammation.

Some commercial cat foods contain ingredients that encourage inflammation. Diets that are high in carbohydrates feed the carb-loving kinds of gut bacteria, which are the kind that cause inflammation.

Eating too much is also a factor: taking in too many calories alters the behavior of cells and increases the immune system’s inflammation response. In addition, extensive research on obesity has established that high levels of body fat lead to chronic inflammation.

Or your cat’s diet may be involved in their symptoms because of a particular food sensitivity or food allergy. A food sensitivity (or food intolerance) is an inability to digest a particular ingredient; for example, lactose intolerance—the inability to digest lactose, a sugar found in dairy products—is very common in cats. In contrast, a food allergy is an overactive immune system response to a trigger, usually a protein source, that the body misinterprets as a threat. In cats, food sensitivities are much more common than true food allergies.

A food sensitivity (like lactose intolerance) can certainly cause vomiting, diarrhea, and other symptoms, but gut inflammation is more likely with a food allergy, since inflammation is an immune reaction.

Periodontal disease (gum disease) has been identified as a contributing factor in many other health conditions, including IBD (via the gum–gut axis). Harmful bacteria that cause trouble in the mouth—like bad breath and red, swollen gums (gingivitis)—can travel farther down the GI tract, triggering an inflammatory immune response in the gut. In addition, inflammation in the mouth and inflammation in the gut influence each other, so your cat’s oral health has a direct effect on their gut health, and vice versa.

Changes to the gut microbiome—the ecosystem of microorganisms that inhabit the intestinal tract—can also cause inflammation. For example, antibiotics can kill important bacteria in the gut that perform anti-inflammatory functions, allowing the inflammation-causing bacteria to flourish and actually worsening gut inflammation. Unhealthy shifts in the composition of the gut microbiome and reduced diversity of gut bacteria are well-known characteristics of IBD.

A cat’s genes are also likely involved in causing IBD. (The disease may be slightly more common in purebred cats, but any cat can develop IBD.) As with IBD in humans, researchers believe that genetic abnormalities in the immune system are partly responsible for feline IBD.

The most likely cause of IBD is the complex interaction of some or all of these potential factors.

The primary goal of any treatment for IBD is to reduce the inflammation of the GI tract. For this reason, steroids like prednisolone (or the related drug prednisone) and budesonide are often prescribed for their anti-inflammatory properties. Antibiotics, such as metronidazole, are also commonly prescribed, because they can have an anti-inflammatory effect when used long-term.

However, steroids and antibiotics typically won’t resolve the underlying cause of inflammation and can lead to further adverse side effects. The best treatment for your cat’s IBD will depend on your cat’s individual case, and finding the optimal approach may take a few rounds of trial and error. Remember that diet, the gut microbiome, environmental elements, and your cat’s genes (or a combination of these factors) may be strongly influencing your cat’s IBD.

The good news is that you can do a lot to help manage your cat’s IBD by making positive changes to your cat’s diet and gut microbiome.

Because gut microbiome imbalance (dysbiosis) is now widely recognized as a prominent feature of IBD, new approaches to treating this disease focus on restoring balance in the gut.

The most effective way to restore a healthy gut microbiome is with fecal microbiota transplantation (FMT), a process in which fecal material from a healthy donor is transferred to the gut of a sick patient. FMT introduces a complete community of healthy microorganisms, which becomes established in the recipient’s gut, resolving the imbalance and reducing inflammation.

A growing body of scientific evidence shows that symptoms of IBD are improved by FMT treatment. FMT can be done via colonoscopy, enema, or endoscopy, but these procedures can be invasive and expensive—and in pets they typically require anesthesia. Fortunately, FMT via oral delivery has been shown to be just as effective.

Our KittyBiome ‍Gut Restore Supplement (an oral FMT capsule) is a convenient, affordable, and antibiotic-free way to reestablish a healthy and balanced gut microbiome. In a 2019 study, 83% of cats with IBD who took the Gut Restore Supplements experienced an improvement in IBD symptoms after one month. For many cats with IBD, reducing their symptoms means a huge improvement in quality of life. Consider Marigold’s story: chronic diarrhea landed this shelter cat on the list for euthanasia, but restoring balance to her gut microbiome resolved her symptoms and turned her life around.

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What are the best ways to introduce a new diet to my cat to rule out food sensitivity?

When do you recommend doing a biopsy over simply treating symptoms?