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Sick cat with vomit on floor

The essentials

  • Inflammatory bowel disease (IBD) involves chronic inflammation of the gastrointestinal tract — Different parts can be affected, including the stomach, small intestine, and large intestine, resulting in weight loss, vomiting, or diarrhea.
  • Biopsies are needed to diagnose IBD — While your vet may suspect IBD based on clinical signs and ultrasound findings, intestinal biopsies are required to know for sure.
  • Veterinary treatment is critical — Treatment generally involves diet change, antibiotics, or immunosuppressive medications such as steroids.

Nothing compares to the joys of being a pet parent, but we all know that it also involves some unpleasant jobs, such as scooping the litter box or cleaning up the occasional hairball. But while cats may have a reputation for vomiting in the most inconvenient places, contrary to popular belief, frequent vomiting or hairballs are NOT normal. If your cat is showing signs of chronic weight loss, vomiting, or diarrhea, they could be dealing with a medical condition, such as inflammatory bowel disease.

What is inflammatory bowel disease? 

Inflammatory bowel disease in cats is a complex, chronic condition characterized by persistent inflammation of the gastrointestinal (GI) tract. This inflammation can involve various types of inflammatory cells and affect several different parts of the GI tract, including the stomach (gastritis), small intestine (enteritis), and large intestine (colitis). When inflammatory cells invade the walls of the GI tract, they cause damage and thickening, affecting your cat’s ability to digest and absorb food, water, and nutrients.

The exact cause of IBD is often unknown; however, several factors may contribute. IBD may involve an inappropriate immune response, where the body’s immune system mistakenly attacks the intestinal lining. Various environmental factors, including food allergies or intolerances, bacterial or parasitic infections, and genetics, can trigger this.

Clinical signs of inflammatory bowel disease in cats

The clinical signs of IBD depend on the severity and which part of the GI tract is affected. For example, if the stomach is affected, your cat may experience chronic vomiting. If inflammation is in the colon, diarrhea will likely be the main symptom.

In general, common symptoms of IBD in cats include:

  • Chronic vomiting
  • Diarrhea (with or without blood)
  • Weight loss
  • Decreased appetite (or, in some cases, ravenous appetite)
  • Lethargy
  • Gas
  • Unkempt fur coat

⚠️ Vomiting (including hairballs) more than once a month may be a sign of IBD or another underlying medical condition, especially if accompanied by weight loss. 

How is inflammatory bowel disease diagnosed? 

IBD shares many clinical signs with other common medical conditions affecting our feline family members. Therefore, your vet will recommend a full workup to reach a diagnosis.

After a thorough medical history and nose-to-tail physical exam, your vet will likely recommend bloodwork, urine, and fecal testing to rule out other causes (such as hyperthyroidism, kidney disease, and intestinal parasites). Most cats with IBD will have normal bloodwork. More specific blood tests can be done to measure levels of B12 and folate, which may be deficient in cats with chronic intestinal disease.

An abdominal ultrasound can provide clues that a cat may be suffering from IBD. Ultrasounds can measure the thickness of the stomach and intestinal walls and evaluate surrounding organs and lymph nodes.

The gold standard for diagnosis of IBD involves collecting biopsies (tissue samples) for evaluation under the microscope. Depending on the location of the inflammation, this will be done under general anesthesia with either an endoscope (small flexible camera and tools) or abdominal surgery, which may cost up to $5000.

Intestinal lymphoma is another common GI disease in cats that causes similar symptoms, including weight loss, vomiting, and diarrhea. The only way to definitively diagnose IBD (and differentiate it from lymphoma) is with intestinal biopsies.  

Some pet parents may not wish to pursue intestinal biopsies. In this case, their vet may begin treatment for IBD. If there is no response to treatment, or if a cat is very ill, then biopsies should be reconsidered.

Treatment options for inflammatory bowel disease in cats

Diet and medication are typically used to manage IBD. In general, IBD may respond to diet changes, antibiotics, or steroids, but it may take some trial and error to find what works best for your cat. Treatments are usually tried in that order as long as a cat is stable. Other common treatments for IBD  include:


Given that parasitic infections can contribute to or exacerbate IBD, a broad-spectrum dewormer is often administered as an initial step. Fecal tests may not always detect all intestinal parasites, so deworming is a precautionary measure to eliminate this potential trigger.


Dietary modification is a cornerstone of IBD treatment in cats. There are two primary approaches:

  • Novel protein diet. This involves switching to a protein source that the cat has never been exposed to before, like venison, duck, or rabbit. This helps reduce the likelihood of food allergies or intolerances triggering inflammation.
  • Hydrolyzed protein diet. In this diet, proteins are broken down into smaller components, making them less likely to provoke an immune response.

Both types of diets aim to minimize antigenic stimulation and allow the GI tract to heal. A high-fiber diet may also be beneficial in cases of colitis (inflammation of the large intestine).


Antibiotics, such as metronidazole or tylosin, may be prescribed to address potential bacterial overgrowth or infection in the gut. These medications also have anti-inflammatory effects.

Immunosuppressive medications

If dietary changes and antibiotics cannot control the inflammation, corticosteroids are often the next step. These potent anti-inflammatory drugs suppress the immune system, reducing the inflammatory response in the GI tract. Prednisolone is commonly used, often starting with a higher dose that tapers down over time. Medications such as cyclosporine and budesonide may also be used. Chlorambucil, a chemotherapeutic agent, may be added if other medications are not effective.

While generally effective, long-term use of steroids and other immunosuppressive medications can have potential side effects, so cats on this therapy require close monitoring.

Vitamin B12

Cats with IBD (and other chronic intestinal diseases) often have difficulty absorbing vitamin B12, which is essential for various bodily functions. Therefore, supplementation is frequently recommended, most commonly via an injection.


Probiotics, prebiotics, and adding fiber to the diet may also be beneficial in some cases.

Treating IBD in cats is an ongoing process that often requires adjustments and modifications as the disease progresses. Even cats who are well-managed may have occasional flare-ups of symptoms. Regular communication with your veterinarian is essential throughout this process.

Prognosis of cats with inflammatory bowel syndrome

IBD is a complex medical condition. While there is no cure, the goal of treatment is to manage inflammation and associated symptoms with long-term, continued treatment. While occasional flare-ups should be expected, the prognosis is generally very good in cats who respond to diet, antibiotics, or immunosuppressive treatments.

Unfortunately, some cats may not respond as well to treatment, and their prognosis is more guarded. In these cases, additional testing could be considered to see if an underlying issue can be found.

Frequently asked questions

Do corticosteroids cause side effects in cats?

The most common side effects of steroids in cats include increased drinking, urination, and appetite. Long-term use can affect the heart, liver, and skin, and increase the risk of diabetes. To minimize these side effects, steroids are usually started at a higher dose and gradually tapered to the lowest effective dose.

How long will a cat live with IBD?

With proper diagnosis, treatment, and management, many cats with IBD can lead happy, healthy lives with normal life expectancies. This may depend on the severity of disease, underlying cause, response to treatment, and owner compliance.

How do you know if your cat has inflammatory bowel disease?

Your vet may suspect inflammatory bowel disease if your cat has typical symptoms such as chronic vomiting, diarrhea, weight loss, and characteristic changes to their intestines on ultrasound. However, intestinal biopsies are the only way to know for sure.

Why is a biopsy needed to diagnose IBD in cats?

A biopsy is crucial for accurately diagnosing IBD and differentiating it from other conditions with similar symptoms, such as intestinal lymphoma. While starting treatment based on symptoms alone is possible, a biopsy provides a definitive diagnosis, allowing your vet to determine an effective treatment plan tailored to your cat’s specific needs.

What happens if IBD is left untreated in cats?

If left untreated, inflammatory bowel disease can lead to continued weight loss, malnutrition, dehydration, anemia, and potentially life-threatening complications like intestinal obstruction or perforation. Chronic inflammation may also increase the risk of intestinal lymphoma. It’s important to see your vet if you are worried your cat may have IBD.