We now realize that the American Cocker Spaniel is susceptible to the heritable accumulation of abnormal amounts of copper in the liver with resultant chronic liver failure. This disease has previously been called chronic active hepatitis. It appears that the problem has been sporadically present in some of the best bloodlines of all three American Cocker Spaniel varieties for at least 30 years. Whether it was present before that, when the cocker spaniel breed was divided into the American and English Cocker Spaniels is not known.
Because of the risk of accumulating excessive copper, especially in families of American Cocker spaniels known to be affected with the problem or closely related to animals with the problem, published data and common sense indicates that reducing dietary sources of copper both in food and in water supplies should be helpful in minimizing the amount of copper. For this reason, commercial or homemade diets should be selected that have lower amounts of copper. Dietary copper restriction should still provide a dietary level equivalent to the NRC minimum of 0.8 mg/1000 kcal ME. This translates to a minimum of 7.3 ppm (7.3 mg/kg) copper for adult maintenance, whereas a truly low copper diet would have < 0.5 ppm copper; but no commercially available diet is this low in copper. Copper-restricted diets are available, and they usually contain about 7-9 ppm (7-9 mg/kg). Some diets that contain higher amounts of copper (18-30 ppm; 18-30 mg/kg) also add higher amounts of zinc, which they claim offsets the higher copper level. [Copper is still an essential nutrient, because of its importance in several key body functions.]
Nutritional therapy in the above situation aids in the management of animals already diagnosed as having copper toxicosis, and for those relatives or families of dogs that are also at increased risk. In addition to feeding diets with lower amounts of copper, zinc is known to bind intestinal copper and prevent its absorption, thereby reducing the amount of copper absorbed. Thus, zinc is often used as a supplement when given at physiological doses to help bind excess copper. Typical doses of zinc for a dog of American cocker spaniel size would be 15 mg of zinc sulfate daily. Zinc acetate or gluconate can also be used at the relatively high levels of 5-10 mg/kg twice daily. Zinc supplement should be given 1 hour before feeding, as food interferes with its absorption. In affected patients, the reduced copper absorption due to zinc supplementation lowers elevated liver copper levels too, presumably by increasing release of liver copper stores to compensate for the lowered intestinal copper absorption.
The protein source in foods for animals with compromised or potentially compromised liver function should be of high quality, so that the diet should have lower amounts of high quality protein, such as would be found in homemade diets designed to provide lower overall protein or diets for senior pets.
Copper Content in Common Foods
Low Copper Content
Medium Copper Content
High Copper Content
Nuts and Seeds
Dodds W J, Donoghue S. Interactions of clinical nutrition with genetics, Chapter 8. In: The Waltham Book of Clinical Nutrition of the Dog and Cat. Pergamon Press Ltd., Oxford, 1994, p.105-117.
Dodds W J. Pet food preservatives and other additives, Chapter 5. In: Complementary and Alternative Veterinary Medicine. Mosby, St. Louis, 1997; pp 73-79.
Volhard W, Brown K L. The Holistic Guide for a Healthy Dog. Howell Book House, New York, 1995, 294 pp.
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