Primary hepatitis in dogs: a retrospective review (2002-2006)

Background: Little is known about etiology, disease progression, treatment outcome, survival time, and factors affecting prognosis in dogs with primary hepatitis (PH). Objectives: To review retrospectively different forms of hepatitis in a referral population, by the World Small Animal Veterinary Association Standardization criteria. Animals: One-hundred and one dogs examined for histologically confirmed PH between 2002 and 2006. Dogs with nonspecific reactive hepatitis were excluded. Methods: Retrospective study. Medical records were reviewed for prevalence, signalment, clinical and clinicopathologic manifestation, outcome, survival time, and prognostic factors for shortened survival. Results: PH occurred in 0.5% of dogs in this referral population. Acute (AH) and chronic hepatitis (CH) were diagnosed in 21 and 67 dogs, respectively. Progression from AH to CH occurred in 5/12 of the repeatedly sampled dogs. CH was idiopathic in 43 (64%) dogs, and was associated with copper accumulation in 24 (36%) dogs. Median survival time was longer in dogs with AH than in dogs with CH (either idiopathic or copper associated), and dogs with lobular dissecting hepatitis had the shortest survival time. Prognostic factors predicting shortened survival were associated with decompensated liver function and cirrhosis at initial examination. Conclusions and Clinical Importance: The majority of PH in dogs is CH. Previous studies appear to have underestimated the etiologic role of copper in both AH and CH. Prognosis is reduced in dogs with hepatic cirrhosis or cirrhosis-related clinical findings. Further research into etiology and treatment effectiveness in all PH forms is needed.