Copper is a mineral that plays an important role in the nutrition of dogs and cats. Copper storage disease (CSD) is becoming increasingly common in dogs but can also occur in cats (albeit rare). It directly affects the liver, which in turn, can cause a domino effect of problems in other systems of the body. What exactly is copper storage disease, and how can it be effectively managed? The key is knowing the symptoms, getting a prompt diagnosis through testing, and following up with a treatment strategy.
What is Copper Storage Disease?
Copper storage disease (CSD) occurs when too much copper is stored in the liver. Also known as copper storage hepatopathy, this type of hepatitis can end in organ failure if not diagnosed and treated. Dogs and cats absorb copper from food in their small intestine. From the small intestine, the copper moves to the liver via the blood, where the liver stores it until the body needs it. Any copper that is not needed gets removed through bile and leaves the body in the animal’s feces and urine. Copper storage disease occurs when there is an excessive amount of copper accumulating in the liver and the body loses the ability to eliminate it. CSD can affect any breed, age, or sex of dogs; however, the condition is more common in females than in males and more common in middle-aged and older dogs. Younger dogs with CSD can present with no outward symptoms. Dog breeds more prone to this disease include Bedlington Terriers, Corgis, Dalmatians, Doberman Pinschers, West Highland White Terriers, Skye Terriers, Keeshonds, American Cocker Spaniels, and Labrador Retrievers.
What causes Copper Storage Disease?
In a healthy animal, the body will balance the amount of copper it stores. If the balance fails, too much copper can build up. High levels of stored copper are toxic to liver cells, leading to liver damage and scarring of the liver (known as cirrhosis). Dogs with other liver diseases such as chronic hepatitis or portosystemic shunts (PSS) are more likely to develop copper storage problems in their liver. The primary ways copper collects in excessive amounts are:
- Excessive copper ingestion in the diet - the excess amount of the essential trace mineral copper in commercial dog and cat food. Pet food regulations call for a minimum of 7.3 mg of copper per kg of food for adult dogs and 5 mg/kg for adult cats, yet there is no maximum limit for copper in pet food. Supplementation may be 25 to 50% over the minimum recommended level in most commercial diets with added copper.
- Genetic-based abnormal copper metabolism (Bedlington Terriers top the list).
- Other primary liver disease that interferes with normal copper elimination
What are the symptoms of Copper Storage Disease?
Not all dogs with excessive liver copper have symptoms even when very high levels of the mineral are present. The most common symptoms of CSD include:
- Poor appetite and weight loss
- Vomiting and/or diarrhea
- Increased thirst and urination
- Abdominal discomfort, swelling, pain
- Fever, weakness, lethargy
- Pale gums, excessive bleeding
- Jaundice and yellowing of the eyes
- Anemia
- Fluid buildup in the abdomen
- Seizures, disorientation, walking in circles
- Dark colored urine and hemoglobin in the urine
How is CSD diagnosed?
- In early disease there may be few symptoms but lab analysis may show elevated liver enzymes.
- In advanced disease, the physical exam will show signs of jaundice, and a palpation of the liver will uncover abnormal size or abdominal discomfort. Your veterinarian can also check for fever, and weakness during the exam.
- Blood work including a CBC (complete blood count) and chemistry panel provide insights into the liver’s function. A low red blood cell count, high liver enzymes (ALT, AST, ALP), and higher than normal bilirubin levels will signal liver problems.
- Urinalysis will evaluate urine concentration, as well as the presence of red blood cells and hemoglobin.
- A Serum bile acids test measures the levels of bile acids in a dog’s blood and is used to diagnose the presence of liver disease and assess overall function.
- X-rays (radiographs) evaluate liver size, shape and internal structure. Ultrasound offers a more detailed view of the liver’s internal structure, detecting changes in liver tissue.
- Blood clotting tests determine whether liver disease has affected the ability of the blood to clot.
- Liver biopsy is the gold standard for diagnosing CSD. This test quantifies the amount of copper stored in the liver. One study showed 30% of canine liver biopsies have evidence of CSD.
- Genetic testing can be used to identify gene mutations that affect copper transport. This testing can be used for early detection in breeds predisposed to CSD.
How is Copper Storage Disease treated?
Pets with CSD require lifetime treatment. The main goal of treating CSD is to reduce the amount of copper in the liver. This is accomplished by decreasing copper consumption and absorption, and helping the body expel the excess copper stored in the liver.
- Feed a copper-restricted diet: I strongly recommend changing to a homemade low-copper diet for animals with CSD. Avoid high copper foods such as beef liver, oysters, mushrooms, tofu and potatoes. Add low-copper foods that support liver function such as poultry (chicken and turkey), celery, carrots, cucumber, kale, cabbage, basil, turmeric, kelp and wheat grass. Most commercial diets contain high amounts of copper, and those formulated with low copper often do not provide enough protein, which is not appropriate in some cases. Pet food regulations call for a minimum of 7.3 milligrams of copper per kilogram of food for adult dogs and 5.0 mg/kg for adult cats. Unfortunately, there is no maximum limit for copper in commercial pet food! If you are feeding a commercial diet, request a complete nutrient breakdown from the company to determine whether the food is appropriate for continued feeding.
- Copper chelators reduce liver copper by binding copper to blood plasma and tissue, which is then excreted in the urine. D-penicillamine (Cupramine) and trientine are drugs that attach to copper in the liver so that it can be removed more easily. Unfortunately, the use of copper-chelating drugs is controversial in Dobermans because the disease tends to progress even with the use of this treatment. Removing excess copper with these drugs can take up to several months. There are also side effects such as vomiting, nausea, lethargy, fever and skin problems. These drugs must be used with caution, as long-term use can develop into copper deficiency.
- Elemental zinc is a common therapy for CSD. Zinc binds with copper and limits its absorption. Zinc gluconate is the most common formulation used and is available over the counter.
- The medication Ursodiol is used to improve bile flow and increase copper excretion.
- SAMe and Vitamin E are antioxidants that are used in treating liver disease, particularly CSD. These supplements shield the liver cells from the harmful effects of too much copper.
Copper is an important trace mineral vital to the production of enzymes and other important cellular processes. There is hope for affected dogs when they get proper treatment. The earlier CSD is diagnosed, the better chances your pet can live a high-quality life. With high-quality nutrition, medical management and careful monitoring, normal liver function can be restored.
Repeat biopsy is the only definitive way to determine how the pet is responding to treatment. Most cases are monitored with lab work rather than another invasive procedure.
