Inflammatory bowel disease (IBD) in cats is a group of chronic gastrointestinal disorders characterised by persistent infiltration of inflammatory cells into the intestinal wall. It is one of the most common causes of chronic vomiting and weight loss in middle-aged and older cats, and often exists alongside pancreatitis and cholangitis as the feline "triaditis" syndrome.
Types and Pathology
IBD is classified by the predominant inflammatory cell type:
- Lymphocytic-plasmacytic enteritis: Most common form; immune-mediated infiltration of lymphocytes and plasma cells
- Eosinophilic enteritis: Less common; may indicate food allergy or parasitism
- Neutrophilic: Rare; often indicates secondary bacterial infection
The distinction between IBD and alimentary small cell lymphoma (SCLT) is clinically important and requires biopsy — SCLT has a similar presentation but different treatment and prognosis.
Clinical Signs
- Chronic or intermittent vomiting (often undigested food or bile)
- Weight loss despite maintained or increased appetite
- Diarrhoea — more prominent with colonic involvement
- Reduced appetite in some cats
- Poor coat condition
- Palpable gut thickening in moderate-severe cases
Diagnosis
Hypocobalaminaemia (low vitamin B12) is strongly associated with IBD and SCLT in cats and supports the diagnosis. Elevated fPLI suggests concurrent pancreatitis. Ultrasound may show intestinal wall thickening and abnormal layering. Biopsy via endoscopy or surgical laparotomy provides definitive diagnosis and histological classification.
Treatment
Dietary management: Novel protein diets (rabbit, venison, duck) or hydrolysed protein diets may resolve dietary-responsive enteropathy without immunosuppression in some cats. Strict dietary compliance is essential during trials.
Corticosteroids: Prednisolone is first-line for immune-mediated IBD. Low doses are used initially, tapered to the minimum effective maintenance dose. Budesonide (a locally-acting steroid with reduced systemic effects) is an alternative.
Cobalamin supplementation: Subcutaneous B12 injections weekly initially, then monthly — essential where hypocobalaminaemia is present; B12 deficiency perpetuates mucosal damage.
Chlorambucil: Added for IBD refractory to steroids, or for SCLT — given weekly or every 2 weeks orally.
Welfare and Long-Term Management
IBD is a manageable but rarely curable condition. Many cats achieve good quality of life with appropriate treatment, though relapses occur. Regular monitoring (weight, body condition, B12 levels, repeat ultrasound) guides dose adjustments. Client education about dietary compliance, medication administration, and signs of relapse is fundamental to sustained welfare outcomes.