IBD (inflammatory bowel disease)
Chronic immune-mediated inflammation of the gut, causing intermittent or persistent vomiting and/or diarrhoea. Common in middle-aged and senior cats and dogs.
Inflammatory bowel disease is not a single condition but a collection of chronic gut inflammations. The body's immune system attacks the gut wall, causing vomiting, diarrhoea, weight loss, and intermittent appetite changes.
Diagnosis is challenging. Bloodwork, faecal tests, and abdominal ultrasound rule out other causes. Definitive diagnosis is by intestinal biopsy under anaesthesia, which is also necessary to differentiate IBD from small-cell lymphoma — the two look identical externally and on imaging but have very different treatment.
Treatment is layered: hypoallergenic or hydrolysed-protein diet trial first, then immunosuppressive medication (steroids, sometimes chlorambucil or cyclosporine), B12 supplementation, and probiotics. Most pets achieve good control even if not cure.
In cats, the link between IBD and small-cell lymphoma is so close that some specialists recommend treating both the same way. Discuss with your vet.