Association Between Liver Copper, Iron and Zinc Values and Inflammator y Lesions of the Liver in Labrador Retrievers

Introduction
A breed predisposition for chronic hepatitis is present in the Labrador retriever. A part of this hepatitis cases is caused by hereditary copper toxicosis. Levels of iron and zinc in the liver may be associated with inflammatory lesions as well. A relation between high liver copper levels, high liver iron levels and inflammatory lesions was described previously in the dog. The association between liver iron and zinc levels and histological lesions in the Labrador retrievers has yet to be elucidated.

Materials and Methods
Liver biopsy samples from 177 Labrador retrievers were analyzed for copper, iron and zinc by Instrumental Neutron Activation Analysis (INAA) and results are reported in mg/kg dry weight liver. Histological grading and staging was performed on histological slides stained with hematoxylin and eosin, rubeanic acid and Perls’ stain. Data on sex and age was collected from the patients’ records. Logistic and linear regression was used to study the relationship between liver copper, iron, zinc levels, inflammatory lesions, age and sex.

Results
Mean concentrations of liver iron were 1605 mg/kg (sd=1284), -zinc 164 mg/kg (sd= 75) and -copper 741 mg/ kg (sd=661). Liver iron concentrations were significantly higher in older animals and female Labradors show a significant higher liver iron concentration than male dogs. Labradors with a non-copper associated hepatitis showed a significant association with high iron levels and low zinc levels in their liver, whereas age and sex did not.

Conclusion
Inflammatory lesions in non-copper associated hepatitis in the Labrador retriever are associated with high iron and low liver zinc concentrations.