Inflammatory bowel disease is not a single disease but a group of chronic gastrointestinal disorders characterized by the infiltration of inflammatory cells into the walls of the stomach, small intestine, or colon. The type of IBD is classified by which inflammatory cells are involved, with lymphocytic-plasmacytic enteritis being the most common form in cats.

The exact cause of feline IBD remains unclear. The prevailing theory is that it results from an abnormal immune response to normal stimuli in the gut, such as food proteins, bacteria, or other environmental factors. Essentially, the cat's immune system overreacts to things that should be harmless, causing chronic inflammation that damages the intestinal lining and interferes with nutrient absorption.

IBD can affect cats of any age, breed, or sex, though it is most commonly diagnosed in middle-aged to older cats. It tends to be a chronic, lifelong condition that waxes and wanes in severity. While it is not typically life-threatening on its own, poorly controlled IBD significantly impacts quality of life and, in some cases, can progress to intestinal lymphoma, a form of cancer.

The relationship between IBD and small cell (low-grade) intestinal lymphoma is an important and sometimes confusing one. These two conditions exist on a spectrum, and in some cats, chronic IBD may eventually transform into lymphoma. This is one reason why proper diagnosis and regular monitoring are so important.

IBD symptoms in cats can range from mild and intermittent to severe and debilitating. The most common symptoms include:

• Chronic vomiting: Often the most prominent symptom, occurring anywhere from a few times a week to daily. The vomit may contain food, bile (yellow liquid), or clear fluid.
• Diarrhea: May be intermittent or chronic. Can range from soft stools to watery diarrhea. Some cats have diarrhea without vomiting, or vice versa.
• Weight loss: Gradual weight loss occurs as the inflamed intestines lose their ability to absorb nutrients effectively.
• Decreased appetite: Some cats become picky eaters or eat less overall. Others maintain a normal appetite despite losing weight.
• Lethargy: Chronic malnutrition and discomfort can cause decreased energy and activity.
• Increased gas or gurgling stomach sounds

Diagnosing IBD requires ruling out other causes of chronic GI symptoms, including parasites, food allergies, pancreatitis, hyperthyroidism, and intestinal lymphoma. Your veterinarian will typically begin with bloodwork, fecal testing, and imaging (abdominal ultrasound). However, the definitive diagnosis of IBD requires intestinal biopsies, obtained either through endoscopy or exploratory surgery. These biopsies allow a pathologist to identify the type and severity of inflammation and to distinguish IBD from lymphoma.

Some owners are understandably hesitant about biopsy procedures. While they do involve anesthesia, they provide crucial information that shapes the treatment plan. Discuss the risks and benefits with your veterinarian to determine the best approach for your cat.

Treatment for feline IBD typically involves a two-pronged approach: dietary modification and medication. Most cats require both for optimal management.

Dietary therapy is a cornerstone of IBD management. Two main dietary strategies are used:

• Novel protein diets: These use a protein source your cat has never eaten before (such as venison, rabbit, or duck) to avoid triggering an immune response to familiar proteins.
• Hydrolyzed protein diets: These contain proteins broken down into pieces so small that the immune system does not recognize them as triggers. Examples include Hill's z/d and Royal Canin Hypoallergenic.

A strict dietary trial lasting 8-12 weeks is often recommended before adding medication, though cats with moderate to severe symptoms may need both simultaneously. During the trial, your cat must eat absolutely nothing besides the prescribed diet, including treats, table food, and flavored medications.

Medications commonly used for feline IBD include:

• Prednisolone (corticosteroid): The most commonly prescribed medication for IBD, effective at reducing inflammation. Treatment typically starts at a higher dose and tapers to the lowest effective maintenance dose. Long-term steroid use carries side effects, but for many cats, the benefits significantly outweigh the risks.
• Budesonide: A locally-acting steroid that may have fewer systemic side effects than prednisolone. Useful for cats who cannot tolerate prednisolone or who have concurrent conditions like diabetes.
• Chlorambucil: An immunosuppressive medication used for severe IBD or cases that do not respond adequately to steroids. Also used if there is concern about progression toward lymphoma.
• Metronidazole: An antibiotic with anti-inflammatory properties in the gut. Sometimes used as an add-on therapy.
• Cobalamin (vitamin B12) supplementation: Many cats with IBD have low B12 levels due to poor absorption. Regular B12 injections can improve energy and appetite.

IBD is a chronic condition that requires ongoing management, but with consistent care, most cats achieve a good quality of life. Many cats respond well to treatment within the first two to four weeks, with reduced vomiting, improved appetite, and weight gain.

Some cats need lifelong medication, while others can eventually be managed with diet alone after a period of medical therapy. Flare-ups can occur, especially during times of stress or dietary indiscretion (eating something outside their prescribed diet). Having a plan for managing flare-ups with your vet can reduce anxiety and get your cat back on track quickly.

Regular veterinary monitoring is important for cats with IBD, typically every three to six months. Bloodwork can track protein levels, B12 status, and liver values (especially if your cat is on long-term steroids). Periodic ultrasound may be recommended to monitor intestinal wall thickness and watch for any changes suggestive of lymphoma.

The connection between IBD and intestinal lymphoma is worth discussing openly with your vet. Not all cats with IBD develop lymphoma, and many live their entire lives with well-controlled IBD. However, if your cat stops responding to IBD treatment or their symptoms worsen despite appropriate therapy, repeat biopsies may be recommended to check for progression. Early detection of lymphoma, particularly the low-grade form, allows for treatment that can extend a cat's life by a year or more.