March 1, 2022 — When we hear the word copper, most of us picture a shiny new penny, or plumbing pipes! But copper also is an important dietary micronutrient. Like many nutrients, too much or too little copper can have important negative health effects. It’s rare to find a dog suffering from copper deficiency, but copper excess is not uncommon and can have serious consequences. Here’s what owners need to know about copper metabolism and how to recognize copper-related diseases in their pet dogs.
Copper Plays an Important Role in Many Body Systems
Copper is a component of several enzymes involved in a diverse set of physiological processes, from hemoglobin and skeletal system formation to immune system and heart function – that’s a lot of different tissues that rely on copper!
Copper is found in many different foods and, after ingestion, it’s absorbed from the intestine. Once in the bloodstream, copper binds to protein and is carried throughout the body. Copper absorption from the intestine is regulated by the needs of the individual, although how this process takes place isn’t completely understood.
Ultimately, copper is stored in the liver, a key point to remember when we talk about disease associated with excess copper. Only small amounts of copper are needed for the body to function properly. The liver helps act as a copper regulator and releases excess copper into bile to provide protection from copper deficiency and toxicity. Excess copper is then excreted from the body in healthy animals.
Copper deficiency is rare, but reported clinical signs in dogs include anemia, loss of hair pigment and rough haircoat, poor growth, reproductive failure (in sexually intact dogs) and neuromuscular problems.
There are three main ways that copper deficiency develops in dogs:
- Food that is low in copper, like rice, eggs, most milk products
- Poor availability of copper to be extracted and used
- Competition from other minerals
Foods that have high copper availability include poultry by-product meal, and chicken, turkey, beef and sheep liver. Copper in soybean meal and corn gluten meal is moderately available, but copper from pork liver and copper oxide is poorly available. This difference is important to remember when crafting a homemade diet.
Zinc is the primary mineral that can compete with copper for absorption, and there is a delicate interplay between the two. Excess zinc can result in lower levels of copper.
One last note on copper deficiency. As mentioned above, copper is important for many tissues of the skeletal system, so growing animals have a higher copper requirement than adult animals.
Copper-Associated Liver Disease
In some dogs, copper can accumulate in the liver over time. This results in damage that leads to liver inflammation (hepatitis), which in turn can progress to liver fibrosis with loss of normal liver tissue (cirrhosis) and ultimately, liver failure. However, in some cases copper accumulates secondary to other liver diseases. Regardless of the inciting cause, progressive loss of normal liver tissue occurs.
Abnormal copper accumulation in the liver also can be associated with a genetic mutation that alters normal copper excretion. The Belington terrier and Labrador retriever are two breeds where the mutation has been identified. In other breeds that have a predisposition to copper accumulation, a clear genetic basis for disease hasn’t been identified but is suspected.
Dog breeds with a higher prevalence of copper-associated disease include:
- Belington terrier
- West Highland white terrier
- Skye terrier
- Doberman pinscher
- Labrador retriever
- American cocker spaniel
There are no clear clinical signs that are specific for copper-associated liver disease. Some dogs may have subclinical disease, meaning that blood tests show liver disease and high levels of copper, but the dogs show no overt signs of illness. Other dogs with severe disease may exhibit clinical signs similar to other diseases that clearly indicate a health emergency. Bloodwork can point toward liver disease. However, a liver biopsy with measurement of copper is essential for establishing a diagnosis of copper-associated liver disease.
Treatment depends on clinical signs coupled with the amount of copper detected in biopsy. Dietary change is a must, and is combined with medications to reduce the amount of copper in the liver. Treatment of any underlying condition is another component of therapy. Your veterinarian can work with you to decide what therapy plan is best for your dog.
The earlier disease is detected, the better the long-term prognosis. Owners of dogs with a predisposition to copper-associated liver disease need to be vigilant and consider routine bloodwork for their dog to monitor for early signs of liver disease. The good news is that many dogs with copper-associated liver disease can enjoy an excellent quality of life!