New Insights on Immune-Mediated Chronic Hepatitis in Dogs—Diagnosis and Long-Term Outcomes

Immune-Mediated Chronic Hepatitis in Dogs

Tarini Ullal, DVM, MS; Sarah Shropshire, DVM, PhD

Background

Immune-mediated chronic hepatitis (IMCH) is considered the most prevalent form of chronic hepatitis in dogs and was previously termed idiopathic chronic hepatitis. The disease involves progressive inflammation and hepatocellular damage due to a self-directed immune response, with parallels to autoimmune hepatitis in humans. Genetic predispositions in certain breeds and a favorable response to immunosuppressive therapy support an autoimmune etiology.

Methods

This review synthesizes current evidence on the pathogenesis, clinical presentation, diagnosis, treatment, and prognosis of IMCH. It draws upon both clinical studies and expert consensus, particularly the ACVIM guidelines, and incorporates unpublished data from the authors’ research on cyclosporine therapy. Diagnostic workflows emphasize liver histopathology, while therapeutic strategies focus on immunosuppressive agents and adjunct supportive care.

Results

IMCH typically presents with nonspecific clinical signs and laboratory findings, often necessitating liver biopsy for definitive diagnosis. Histologic features include lymphoplasmacytic portal inflammation, interface hepatitis, and hepatic fibrosis. Immunosuppressive therapies—especially modified cyclosporine—were effective, achieving biochemical remission in 80% of dogs. Prednisolone, mycophenolate, and adjuncts like hepatoprotectants were also used, though corticosteroids posed more side effects. Prognosis was favorable when treatment was initiated before advanced fibrosis, and many dogs achieved long-term disease control, though most required life-long therapy.

Limitations

There is no definitive non-invasive test for IMCH; diagnosis relies on exclusion of other causes and histological confirmation. Histologic variability across liver lobes can challenge accurate diagnosis. Long-term outcome data from prospective controlled trials are lacking, and most evidence is retrospective or anecdotal. The use of unpublished data limits external reproducibility.

Conclusions

IMCH is a treatable yet progressive disease that requires early diagnosis and tailored immunosuppressive therapy. Histologic confirmation with exclusion of other causes is essential. Cyclosporine appears particularly effective and well-tolerated. Long-term management and monitoring are crucial, with most patients requiring ongoing immunosuppression. A proactive approach can lead to significant improvement in quality of life and longevity.

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