Copper-associated hepatitis in Labrador Retrievers

Labrador Retrievers with elevated hepatic copper levels have been reported; however, it is unclear whether primary copper-associated hepatitis occurs in this breed. The objective of this study was to determine whether copper-associated hepatitis could be identified in Labradors by reviewing cases from the Diagnostic Center for Population and Animal Health, Michigan State University. Sixteen Labrador Retrievers (3 male, 12 female, and 1 of undetermined sex) between 4 and 11 years old, had multifocal and coalescing, centrilobular hepatitis characterized by macrophages with abundant intracytoplasmic copper and hemosiderin. Other lesions included multifocal, centrilobular and random, pigmented granulomas, hepatocellular necrosis, intrahepatic cholestasis, centrilobular or bridging fibrosis, and occasionally, pseudolobule formation. In rhodanine-stained sections, copper was concentrated in the cytoplasm of centrilobular and midzonal hepatocytes and in macrophages, which is consistent with copper-associated hepatitis. In 12 of the dogs, quantitative liver copper levels were available, and in all but 2 dogs the levels were greater than 2,000 parts per million dry weight (ppm dw). One dog had a liver copper level of 1,990 ppm dw and one dog with advanced hepatic cirrhosis had a level of 1,490 ppm dw. The findings suggest that primary copper-associated hepatitis likely occurs in Labrador Retrievers.