Inflammatory bowel disease, or IBD, describes a group of chronic gut disorders in which inflammatory cells infiltrate the walls of the stomach and intestines. The walls thicken, digestion and absorption suffer, and the cat’s symptoms wax and wane for months. IBD is one of the most common causes of chronic vomiting and diarrhea in middle-aged and older cats, and it is easily mistaken for fussiness or “just a sensitive stomach.”
What Is Actually Happening
The name changes with the location. Inflammation in the stomach is called gastritis; in the small intestine, enteritis; in the colon, colitis. The most common form, lymphocytic-plasmacytic enteritis, involves immune cells called lymphocytes and plasma cells. Current evidence points to a complex interaction between the immune system, food antigens, gut bacteria, and genetics, rather than a single cause. In some cats, IBD travels with inflammation of the liver and pancreas, a combination vets refer to as triaditis.
Where the Inflammation Sits Shapes the Signs
| Region inflamed | Typical signs |
|---|---|
| Stomach | Chronic vomiting, sometimes of food or fluid |
| Small intestine | Weight loss, poor appetite, voluminous diarrhea |
| Colon | Small loose stools with mucus or fresh blood, straining |
Lethargy and a dull coat often accompany all three. Because these signs overlap with many other diseases, they should always prompt a vet visit rather than a wait-and-see approach.
Diagnosis Is a Process of Ruling Out Mimics
There is no single blood test for IBD. Vets work through the lookalikes first: fecal exams for parasites, blood panels to check thyroid and organ function, tests for feline leukemia and immunodeficiency viruses, and an abdominal ultrasound to measure intestinal wall thickness. Blood levels of cobalamin and folate show how well the gut is absorbing nutrients. The definitive answer comes from intestinal biopsies, taken with an endoscope or during surgery, which show the type and depth of inflammation. Biopsies also matter because intestinal lymphoma, a cancer, can look identical to IBD on scans, and the two are managed very differently.
Treatment Starts With Diet
Dietary change is both a diagnostic tool and a treatment. Many cats respond to a strictly-run food trial using a hydrolyzed diet, in which proteins are broken into fragments the immune system does not recognize, or a novel-protein diet built around a protein the cat has never eaten. The trial must be pure: no treats, table scraps, flavored medications, or food from other pets, typically for eight to twelve weeks. Cats that will not accept the new food should never simply be allowed to go hungry, because a cat that stops eating can develop hepatic lipidosis, a dangerous liver condition.
When Medication Is Needed
- Corticosteroids such as prednisolone are the mainstay for reducing gut inflammation once diet alone is insufficient.
- Metronidazole may be added for its anti-inflammatory and antiprotozoal effects.
- Stronger immunosuppressants such as chlorambucil are reserved for refractory cases or when lymphoma is a close differential.
- Cobalamin supplementation corrects the deficiency common in small-intestinal disease.
All medications and dose adjustments belong to the veterinarian; chronic gut disease in cats responds best to a monitored, stepwise plan rather than repeated home experiments.
If your cat has vomited more than occasionally for more than a couple of weeks, is losing weight, or has persistent loose stools, schedule a veterinary exam. IBD is rarely cured, but with the right diet and medication plan, most cats regain comfortable, stable digestion and a normal life span.