Low alanine aminotransferase activity gene variant in a Siberian Husky with copper-associated hepatopathy

BACKGROUND: Alanine aminotransferase (ALT) is commonly used as a marker of hepatocellular injury. Increased serum ALT activity due to hepatocyte injury occurs in copper-associated hepatopathy (CuCH) and other necroinflammatory liver conditions. Blood ALT concentrations are frequently used to monitor therapy in cases of CuCH. Low serum ALT activities have been associated with an allele at a CFA13 locus. CASE PRESENTATION: A 9-year-old female spayed Siberian Husky was diagnosed with CuCH (hepatic copper dry weight 2680 µg/g [normal, 120–400 µg/g; toxic, > 1500 µg/g]) and a normal ALT (78 U/L; reference range, 10–125 U/L). Mild hepatocellular necrosis was evident histologically. Genetic testing (Embark) revealed that the dog was heterozygous for the low ALT activity gene allele. CONCLUSIONS: This case report illustrates the clinical implications for diagnosing and managing necroinflammatory liver disease such as CuCH in dogs with a low ALT activity genotype.