Dietary Management of Hepatic Copper Accumulation in Labrador Retrievers

Background Copper-associated chronic hepatitis (CACH) recently has been recognized in the Labrador Retriever as an inherited disorder with a late onset of clinical signs. No studies have investigated dietary management for the long-term treatment of this disease or for its potential in delaying the onset of clinical signs in subclinical cases. Objectives To investigate the effects of a low-copper diet and zinc gluconate on hepatic copper concentrations in Labrador Retrievers with abnormal hepatic copper concentrations. Animals Twenty-four client-owned Labradors that were related to patients affected with CACH and that had been diagnosed with increased hepatic copper concentrations. Methods Hepatic copper concentrations were assessed before and after an average of 8 and 16 months of treatment. During this time, all dogs were fed exclusively a low-copper diet. In addition, dogs were assigned to 1 of 2 groups in a randomized double-blind manner to receive a supplement of zinc gluconate or placebo. Results Twenty-one dogs completed the study. Hepatic copper concentrations decreased in both groups at recheck 1 (n = 21; group 1, P < .001; group 2, P = .001) and at recheck 2 (n= 16; group 1, P = .03; group 2, P = .04). No difference in hepatic copper concentrations was found between the 2 groups before treatment (P = .65), at recheck 1 or at recheck 2 (P = .52-.79). Conclusions and Clinical Relevance Feeding low-copper diets to Labradors is effective in decreasing hepatic copper concentrations. Adjunctive treatment with zinc does not appear to increase the copper-lowering effects of dietary management.