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Dietary and hepatic copper and zinc levels in labrador retrievers
A D VA N C E S
hepatic copper concentration. Zinc salts are often used in the treatment of Wilson’s disease, a common form of copper toxicosis in humans. Rather than promoting cupriuresis, like the copper chelators D-penicillamine or trientene, zinc blocks copper uptake in the enterocytes. Therefore, zinc is preemptive therapy and used in patients prior to developing clinical signs and for maintenance therapy. Zinc induces the endogenous copper chelator metallothionein when it is absorbed into the enterocytes. When copper enters the enterocyte, zinc is displaced by copper from the metallothionein binding site, forming a coppermetallothionein complex. The enterocyte, including copper, is shed into the feces. Currently, no data are available on the effects that dietary copper and zinc concentrations ,which are regularly present in commercial dry diets, have on hepatic copper and zinc concentration in Labrador retrievers.
Objectives
DIETARY AND HEPATIC COPPER AND ZINC LEVELS IN LABRADOR RETRIEVERS Background Copper-associated hepatitis in Labrador retriever dogs is a complex hereditary disease. Copper accumulation in the canine liver progresses over several years without apparent clinical signs in early stages, but in later stages, chronic hepatitis and cirrhosis develop and result in liver failure at middle or old age. When diagnosed after clinical signs are apparent, the disease often has a fatal course within a few months. The National Research Council (NRC) provides recommendations for pet food nutrient composition with the aim to meet requirements of dogs with minimal risk of deficiency or toxicity. The guidelines do not contain information on the appropriate dietary intake for animals with metal metabolism abnormalities. Decreased dietary copper concentrations appear to be beneficial in treating copper toxicity. Labrador retrievers that have an increased hepatic copper concentration after D-penicillamine treatment and are fed a diet with a copper content of 1.23 mg/1,000 kcal metabolizable energy (ME) have a significant decrease in their
To investigate whether dietary copper and zinc levels of commercially available dry diets are associated with hepatic copper and zinc concentrations in Labrador retrievers.
Procedure Fifty-five Labrador retrievers were fed a single brand and type of commercial dry food for at least 1 year. Of these, 44 dogs were family members of Labrador retriever families with copper-associated hepatitis. Liver biopsies, blood samples, and diet samples were obtained. Liver specimens were scored histologically, and copper and zinc concentrations were quantified. Dietary concentrations of copper and zinc were measured. The association between dietary intake of copper and zinc and hepatic copper and zinc concentrations was investigated.
Results High dietary copper and low dietary zinc levels were significantly associated with high hepatic copper levels. No association between dietary intake and hepatic zinc was present.
Author Conclusion Dietary copper and zinc at current levels in commercially available dry dog food can influence hepatic copper concentration
PAG E 7
PAG E 8
A D VA N C E S
and can be a risk factor for the development of copper-associated hepatitis in Labrador retrievers with a genetic susceptibility to copper accumulation.
Inclusions One figure, 2 tables, 30 references.
Editor Annotation The results of this study revealed that high dietary copper and low zinc levels are significantly associated with high hepatic copper levels. There was no association between dietary zinc intake and hepatic zinc. Clinicians should be aware that dietary copper can influence copper levels in the liver, and special attention to reducing dietary copper is warranted for those breeds of dogs that have copper-associated hepatopathies. (MM) Fieten H, Hooijer-Nouwens BD, Biourge VC, et al. Association of dietary copper and zinc levels with hepatic copper and zinc concentration in Labrador Retrievers. J Vet Intern Med 2012;26:1274-1280.
hepatic copper concentration. Zinc salts are often used in the treatment of Wilson’s disease, a common form of copper toxicosis in humans. Rather than promoting cupriuresis, like the copper chelators D-penicillamine or trientene, zinc blocks copper uptake in the enterocytes. Therefore, zinc is preemptive therapy and used in patients prior to developing clinical signs and for maintenance therapy. Zinc induces the endogenous copper chelator metallothionein when it is absorbed into the enterocytes. When copper enters the enterocyte, zinc is displaced by copper from the metallothionein binding site, forming a coppermetallothionein complex. The enterocyte, including copper, is shed into the feces. Currently, no data are available on the effects that dietary copper and zinc concentrations ,which are regularly present in commercial dry diets, have on hepatic copper and zinc concentration in Labrador retrievers.
Objectives
DIETARY AND HEPATIC COPPER AND ZINC LEVELS IN LABRADOR RETRIEVERS Background Copper-associated hepatitis in Labrador retriever dogs is a complex hereditary disease. Copper accumulation in the canine liver progresses over several years without apparent clinical signs in early stages, but in later stages, chronic hepatitis and cirrhosis develop and result in liver failure at middle or old age. When diagnosed after clinical signs are apparent, the disease often has a fatal course within a few months. The National Research Council (NRC) provides recommendations for pet food nutrient composition with the aim to meet requirements of dogs with minimal risk of deficiency or toxicity. The guidelines do not contain information on the appropriate dietary intake for animals with metal metabolism abnormalities. Decreased dietary copper concentrations appear to be beneficial in treating copper toxicity. Labrador retrievers that have an increased hepatic copper concentration after D-penicillamine treatment and are fed a diet with a copper content of 1.23 mg/1,000 kcal metabolizable energy (ME) have a significant decrease in their
To investigate whether dietary copper and zinc levels of commercially available dry diets are associated with hepatic copper and zinc concentrations in Labrador retrievers.
Procedure Fifty-five Labrador retrievers were fed a single brand and type of commercial dry food for at least 1 year. Of these, 44 dogs were family members of Labrador retriever families with copper-associated hepatitis. Liver biopsies, blood samples, and diet samples were obtained. Liver specimens were scored histologically, and copper and zinc concentrations were quantified. Dietary concentrations of copper and zinc were measured. The association between dietary intake of copper and zinc and hepatic copper and zinc concentrations was investigated.
Results High dietary copper and low dietary zinc levels were significantly associated with high hepatic copper levels. No association between dietary intake and hepatic zinc was present.
Author Conclusion Dietary copper and zinc at current levels in commercially available dry dog food can influence hepatic copper concentration
PAG E 7
PAG E 8
A D VA N C E S
and can be a risk factor for the development of copper-associated hepatitis in Labrador retrievers with a genetic susceptibility to copper accumulation.
Inclusions One figure, 2 tables, 30 references.
Editor Annotation The results of this study revealed that high dietary copper and low zinc levels are significantly associated with high hepatic copper levels. There was no association between dietary zinc intake and hepatic zinc. Clinicians should be aware that dietary copper can influence copper levels in the liver, and special attention to reducing dietary copper is warranted for those breeds of dogs that have copper-associated hepatopathies. (MM) Fieten H, Hooijer-Nouwens BD, Biourge VC, et al. Association of dietary copper and zinc levels with hepatic copper and zinc concentration in Labrador Retrievers. J Vet Intern Med 2012;26:1274-1280.