Copper is not a nutrient that many owners contemplate, until it is associated with disease. In health, copper plays a role in the formation of a dog’s bones, connective tissue, collagen, and myelin (the protective covering of nerves). Copper also helps the body absorb iron, making it an important part of red blood cell function. It also acts as an antioxidant, is a part of many enzymes, and is necessary for the formation of melanin, the pigment that darkens hair and skin.
Copper is found in meat, liver, fish, whole grains, and legumes and is typically added as a supplement to commercially prepared foods. Copper deficiency is extremely unlikely if a dog eats a nutritionally balanced diet. Problems are most often associated with copper excess, not generally from an improperly formulated diet but instead due to inborn errors of metabolism that eventually cause too much copper to accumulate in the liver. At excessively high levels, copper results in oxidative stress, inflammation, and eventually to liver scarring (cirrhosis) and failure.
Liver disease associated with abnormal copper metabolism has a strong genetic component and is seen most frequently in Bedlington Terriers, West Highland White Terriers, Skye Terriers, Dalmatians, Labrador retrievers, and possibly Doberman Pinschers. Symptoms can include loss of appetite, weight loss, depression, jaundice, vomiting, diarrhea, increased thirst and urination, accumulation of fluid within the abdomen, and behavioral changes. Liver disease can usually be diagnosed based on the results of blood work but determining that copper is responsible requires liver biopsies that are evaluated using special stains
Treatment for this type of liver disease centers on reducing the amount of copper that gets stored in the liver. Chelating agents like trientine or D-penicillamine bind to copper and aid in its excretion from the body. Zinc changes the way in which copper is absorbed and metabolized and ameliorates its toxic effects. Zinc supplements are often prescribed for maintenance after a dog has been decoppered (I love that word) with chelating agents. Generalized liver support is also important and can include antioxidants like Vitamin E and S-Adenosylmethionine.
Dietary therapy plays an important role in managing copper associated liver disease. The ideal food is low in copper, high in zinc, high in B-vitamins (which are often deficient with liver disease), and contains adequate but not excessive amounts of high quality protein since eating too much protein can adversely affect brain function in dogs with liver disease. The diets should be tasty enough to encourage dogs to eat and nutrient dense so that pets with marginal appetites don’t have to take in large volumes. Feeding multiple meals throughout the day is often necessary to maintain a dog’s body condition.
Prescription “liver diets” are available that meet most if not all of these parameters. Homemade diets prepared according to a recipe designed by a veterinary nutritionist familiar with the dog’s case are another good option, particularly for dogs with poor appetites. It is also important to avoid feeding these dogs foods that are high in copper, including shellfish, liver, and mineral supplements that have not been prescribed by the pet’s veterinarian.
Dr. Jennifer Coates