RESUMO
BACKGROUND: Copper-associated hepatitis (CAH) has been well described in Labrador Retrievers. However, the association of CAH with proximal renal tubular dysfunction in this breed has not been characterized. OBJECTIVES: To report clinical features, hepatic and renal histopathologic findings, tissue copper concentrations, and outcome of Labradors with CAH and proximal renal tubular disease. ANIMALS: Nine Labrador Retrievers with renal glucosuria and biopsy-confirmed CAH. METHODS: Clinical, clinicopathologic, and light microscopic findings were retrospectively reviewed. Rhodanine staining or atomic emission spectroscopy was performed on all hepatic samples and available renal tissue (4 dogs) to assess copper concentrations. RESULTS: Eight dogs had a history of polyuria and polydipsia, and all dogs had increased serum bilirubin concentrations. Five dogs had hyperchloremic metabolic acidosis. Three dogs with acidemia had paradoxical alkalinuria. All renal specimens had increased copper concentrations. Renal tubular vacuolization, degeneration, and regeneration were observed on light microscopy. Four dogs died within 10 days of diagnosis. One dog survived 2 months; 4 dogs survived more than 1 year. In long-term survivors, including 2 that did not undergo immediate copper chelation, resolution of renal tubular dysfunction occurred within weeks to months. CONCLUSIONS AND CLINICAL IMPORTANCE: Labrador Retrievers with CAH can develop clinical and laboratory evidence of renal tubular dysfunction in association with increased renal copper concentrations. Given the rarity of renal tubular disorders, detection of renal glucosuria and increased ALT activity in a Labrador Retriever is suggestive of CAH. Although renal tubular dysfunction may indicate advanced disease, successful long-term outcome is possible with a variety of therapies.