Copper Toxicosis (COMMD1) in Bedlington terriers

Copper toxicosis (COMMD1 for short) is a hereditary health condition that can affect certain dog breeds, most notably the Bedlington terrier. Dogs with the condition build up an abnormally high accumulation of copper in the tissue of their livers, which leads to damage to the cells of the liver, and chronic and damaging inflammation of the liver too, known as hepatitis.

Over time, this results in cirrhosis of the liver, which is a form of scarring, and after this point, the condition usually results in death.

Because the condition it hereditary, it is passed on through the gene pool of affected dogs from parents to their offspring, and whether or not it is passed on through the breed line depends on the status of the two parents dogs when it comes to the condition.

In order to reduce the incidences of copper toxicosis in breeds known to be susceptible to the condition, The Kennel Club oversees a health screening scheme for Bedlington terriers, which enables Bedlington terrier owners to get their dogs tested for the markers of the condition prior to breeding from them, in order to allow them to make an informed decision about whether or not to breed.

In this article, we will look at copper toxicosis in Bedlington terriers in more detail, including how the heredity of the condition works, and how to get your dog tested. Read on to learn more.

More about copper toxicosis

All dogs need small amounts of the micronutrient copper in order to be healthy, but abnormally high concentrations of copper in the blood can cause significant problems. The liver is responsible for filtering and metabolising nutrients and detoxifying the blood that passes through it, as well as controlling the body’s copper levels.

In healthy dogs, the body absorbs copper in the gut before passing it to the hepatic portal, which in turn transports it to the liver. Special cells in the liver absorb the copper present and regulate it so that it can be circulated around the body and released into the blood stream, and an excess of copper is eliminated by the dog’s bile duct.

Copper toxicosis leads to an abnormally high build-up of copper in the body, which leads to too much copper being absorbed, which the body cannot then properly eliminate. In turn, this causes copper to accumulate in the liver cells in dangerously high amounts, which leads to the cirrhosis and damage to the liver that are the signature of the condition, and which can ultimately prove fatal.

This process is usually slow and progressive, as the liver needs to take a reasonable amount of damage and scarring before its functions are compromised.

What sort of dogs can be affected by the condition?

In the UK, the Bedlington terrier is the breed considered to be at the highest risk of copper toxicosis, and when the condition was first widely investigated during the 1980’s, as many as a third of all dogs of the breed carried at least one mutated gene for the condition.

However, thanks to testing and selective breeding since that time, the prevalence of the condition has fallen, with current estimates placing around 10% of dogs of the breed as carriers of or affected by the condition.

Cross breed dogs with some Bedlington terrier ancestry may potentially inherit one of the faulty genes that lead to the condition too, but as such dogs are outcrossed to other breeds, it is relatively unlikely for any given non-pedigree dog to be affected.

How does the heredity of the condition work?

Copper toxicosis is an autosomal recessive condition, which means that the heredity of the condition and whether or not any given puppy inherits it depends on the status of both of their parent dogs and how their combined genes express.

Dogs can be either totally clear of the condition, a carrier for the condition, or affected by the condition themselves.

• Two clear dogs will produce clear puppies.
• Two affected dogs will produce affected puppies.
• Two carriers will produce a mixed result of 50% carrier, 25% clear and 25% affected.
• A carrier and an affected dog will produce 50% carriers and 50% affected.
• A clear dog and a carrier will produce 50% clear and 50% carrier.
• A clear dog and an affected dog will produce a litter of carriers.

Getting your dog tested

If you own a Bedlington terrier that you are considering breeding from, it is wise to find out the status of your own dog and the dog you intend to match them with before going ahead, in order to prevent the condition from being passed on to the next generation.

For potential puppy buyers, asking about the status of the parent dogs is important too.

In order to get a dog tested, all you need to do is take a DNA sample (your vet can do this) and send it off to one of The Kennel Club’s approved laboratories, who will then return the results to you.