Hepatic copper concentrations in Labrador Retrievers with and without chronic hepatitis: 72 cases (1980-2010)

Objective To evaluate differences in hepatic copper concentrations in Labrador Retrievers with and without chronic hepatitis. Design-Retrospective case-control study. Sample-Liver tissue specimens from 36 Labrador Retrievers with chronic hepatitis and 36 age- and sex-matched Labrador Retrievers without chronic hepatitis (control dogs). Procedures-Liver tissue specimens were obtained during 2 study periods (1980 to 1997 and 1998 to 2010). For each tissue specimen, a histologic score was assigned independently by each of 2 interpreters, and the hepatic copper concentration was qualitatively determined via rhodanine staining and quantitatively determined via atomic absorption spectroscopy. Results-Mean hepatic copper concentration was significantly higher in dogs with chronic hepatitis (614 mu g/g of dry weight [range, 104 to 4,234 mu g/g of dry weight]), compared with that in control dogs (299 mu g/g of dry weight [range, 93 to 3,810 mu g/g of dry weight]), and increased significantly overtime. A higher proportion of liver tissue specimens collected during the 1998-2010 study period had hepatic copper concentrations >400 mu g/g of dry weight (the upper limit of the reference range), compared with the proportion of liver tissue specimens collected during the 1980-1997 study period. The qualitative copper score did not accurately predict quantitative hepatic copper concentration in 33% of study dogs. Conclusions and Clinical Relevance-Results suggested that the increase in hepatic copper concentrations in Labrador Retrievers with and without chronic hepatitis over time may be the result of increased exposure of dogs to environmental copper, most likely via the diet. (J Am Vet Med Assoc 2013;242:372-380)