Copper Toxicosis (Labrador Retriever Type)

General Information: Copper toxicosis (Labrador Retriever type) is an inherited metabolic disease affecting dogs, leading to chronic liver failure. Dogs with this condition have a reduced ability to excrete dietary copper, resulting in excessive copper accumulation in tissues and organs, including the liver. This can cause liver damage and cirrhosis. The age of onset and speed of disease progression can vary, but most affected dogs present in middle age with non-specific signs of liver dysfunction such as weight loss, lethargy, weakness, vomiting, diarrhea, and abdominal pain. In the late stages, dogs may develop signs of liver failure, including abdominal swelling, jaundice, and neurological dysfunction. Dogs with one or two copies of the mutation may benefit from specific therapies.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected

One Variant Detected: Dog Possibly Affected

No Variants Detected: No Effect

Gene / Testing Information: Genetic testing of the ATP7B gene will reliably determine if a dog is at increased risk for copper toxicosis (Labrador Retriever type). This condition is inherited in an autosomal incomplete dominant manner, meaning that dogs only need one copy of the mutated gene to be at increased risk. Although copper toxicosis is most commonly seen in dogs with two copies of the mutated gene, carrier dogs (with one copy) have a lower risk of copper toxicity but are still at higher risk than dogs without the mutation. Therefore, dogs with one or two mutant copies of the gene are considered at risk for copper toxicosis. Additionally, this disease appears to be sex-influenced, with female dogs inheriting one or two copies of the ATP7B mutation at higher risk of developing clinical disease compared to males. Since multiple genetic and environmental factors contribute to copper toxicosis, a normal ATP7B result does not exclude the disease, and an at-risk result does not guarantee the development of the disease. Given the high frequency of the ATP7B mutation among Labradors, it is recommended to breed dogs with the mutation to those without it rather than removing them from breeding programs to maintain genetic diversity and prevent other genetic diseases in Labradors.

Note: A mutation in the ATP7A gene has been shown to decrease copper accumulation in dogs with one or two copies of the ATP7B mutation. This effect is more pronounced in males, although the ATP7A mutation is not entirely protective in either sex. Because multiple factors contribute to copper toxicosis, dogs with the ATP7A mutation may still be at risk if they also carry the ATP7B mutation or other unknown mutations.

Genetic testing of the ATP7A gene will reliably determine if a Labrador Retriever is a genetic carrier of the copper toxicosis modifier. The copper toxicosis modifier decreases the risk of excessive copper accumulation in an X-linked incomplete dominant manner. Male dogs at risk due to the ATP7B mutation only need one copy of the semi-protective ATP7A mutation to reduce their risk. Female dogs with the ATP7B mutation and one copy of the ATP7A mutation may still be at higher risk due to another normal copy of the ATP7A gene. Females with two copies of the ATP7A mutation are more protected than those with one copy. Male dogs with one copy of the ATP7A mutation tend to accumulate less copper than their female counterparts when also carrying the ATP7B mutation. Dogs without the ATP7B mutation are not affected by the ATP7A mutation.