Liver Disease due to Copper Accumulation
|
|
|
|
Canine copper hepatotoxicosis, also called copper storage disease, is a condition that is caused by an excessive accumulation of copper in the liver. It occurs more frequently in certain breeds of dogs. It can be a serious disease that, left untreated, can be fatal. Who is at risk?Canine copper hepatotoxicosis most commonly affects the Bedlington Terrier, Doberman Pinscher, Skye Terrier, and West Highland White Terrier. Bedlington Terriers develop chronic hepatitis as a result of an inherited metabolic defect that causes copper to remain in the liver rather than be eliminated from the body. In the United States, as many as 66% of Bedlington Terriers may be affected. The Doberman Pinscher is at an increased risk for developing chronic hepatitis and cirrhosis. A genetic basis is suspected because of the high frequency in this breed. Liver copper concentrations are increased in many but not all affected dogs. The increased copper may be an incidental finding or this breed may have liver damage at lower copper levels than other breeds. Chronic hepatitis and cirrhosis associated with copper accumulation in the liver has been reported in genetically related Skye Terriers. It is speculated to be a disorder of bile secretions. West Highland White Terriers are at increased risk of developing chronic hepatitis and cirrhosis. Excess liver copper accumulation is a familiar trait but the mode of inheritance has not been established. Many West Highland White Terriers have increased liver copper levels but not to an extent that clinical illness is seen. What are the causes?The excess accumulation of copper in the liver may be caused by an abnormal binding of copper to certain proteins in the liver or abnormal secretion of copper in the bile. What are the symptoms?Dogs with copper storage disease show a range of symptoms depending on the amount of damage to the liver. Symptoms may include bleeding from the gums or the nostrils, ascites, jaundice, vomiting, diarrhea, and weight loss. Acute release of the copper from the liver may result in red blood cell destruction causing anemia, hemoglobinemia (free hemoglobin in the blood), and hemoglobinuria (hemoglobin in the urine). How is copper storage disease diagnosed?The symptoms and breed of dog will cause a veterinarian to suspect copper storage disease. Blood tests may indicate an increase in the liver enzymes such as serum alanine aminotransferase (see Symptoms and Diagnosis of Liver Disorders). A liver biopsy is necessary for a definitive diagnosis and to determine the amount of copper present. What is the treatment?Treatment includes the use of penicillamine to chelate (bind) and increase urinary excretion of copper. Zinc acetate helps to bind copper preventing its absorption. Affected dogs are placed on a low copper diet, preferably with less than 0.5 PPM of copper. Extra vitamin E is supplied as an antioxidant therapy to help reduce damage to the liver. Vitamin C should be avoided in dogs with copper accumulation because it may increase the copper's damage to the liver. The use of copper chelating agents in the Doberman Pinscher is controversial since the disease tends to progress even if copper levels are decreased to normal. How is copper storage disease prevented?Elimination of the disease from breeds at high risk of developing it depends on being able to show how it is inherited and then to remove those dogs who carry the gene from breeding programs. A genetic marker for copper toxicosis in the Bedlington Terrier has been identified. A liver registry has been formed for Bedlington Terriers who are unaffected as determined by liver biopsy taken after one year of age. For more information, contact the Canine Liver Registry, Veterinary Medical Data Base, 1235 SCC-A, Purdue University, West Lafayette, IN 47907-1235 or the Orthopedic Foundation for Animals (OFA), 2300 Nifong Blvd., Columbia, MO 65201. Jennifer Prince, DVM
|
