Alexander Disease or Leukodystrophy in the Labrador Retriever

The Labrador retriever is the UK’s most popular large dog breed, and according to Kennel Club registration statistics, it was also the most popular and commonly owned pedigree dog breed in the UK overall from 1991 right through until the latter half of 2018, when the breed was finally overtaken by the French bulldog.

There are numerous good reasons behind the Labrador’s enduring popularity, including their incredibly kind natures, amenable dispositions, gentle manner, high energy levels, and high intelligence. Dogs of the breed are also incredibly versatile and equally well suited to a wide variety of working roles as to life as domestic pets, and this adaptability is part of what has helped to ensure that the breed is in great demand with owners of all types and from all walks of life.

Labradors also tend to be hardy, robust dogs that are generally healthy and fit for life, but like most pedigree breeds, a number of hereditary health problems can be found within certain breed lines that can affect the health and longevity of dogs affected by them.

One of these hereditary health conditions is called Alexander disease or leukodystrophy, and whilst this is still considered to be a rare disorder even within Labradors, it is also a very serious condition that usually proves fatal to affected dogs at a young age.

Fortunately, there is a DNA testing scheme in place for the Labrador retriever breed that allows owners of dogs of the breed to find out their own dogs’ status for the condition, and this information can help breeders to arrange healthy mating matches.

In this article we will look at Alexander disease or leukodystrophy in the Labrador retriever in more detail, examining how the condition affects dogs, how it is transmitted, and how the testing scheme for Alexander disease in the Labrador retriever works. Read on to learn more.

What is Alexander disease or leukodystrophy?

Alexander disease (AxD) or leukodystrophy is an uncommon type of degenerative neurological disorder of a specific type that can be found in the Labrador retriever dog breed. The condition affects the body’s myelin, which is a lipid-rich fatty substance that the body needs in order to protect nerves and nerve cells. Alexander disease causes the body to lose myelin, which results in a range of symptoms and problems such as loss of balance, lack of coordination when walking or moving round, and a gradual and progressive muscle weakness that worsens over time.

Ultimately, Alexander disease in the Labrador retriever will make the dog unable to move and get up and down, resulting in a final paralysis that cannot be cured or reversed and that means that the dog is usually euthanised to prevent further suffering.

What type of dogs may develop Alexander disease or leukodystrophy?

There are a few different types of leukodystrophy, but the type that can be found within the Labrador retriever dog breed is called Alexander Disease (AxD), and it tends to affect younger dogs, almost exclusively those under the age of around four years old. In many Labradors with the condition, it will become apparent very early on, often at just 4-6 weeks of age.

Males and females are equally likely to be affected by the condition, and if any given dog has a parent or other close relative that was affected themselves, this increases the risk factors for other dogs that share their genetic ancestry.

How is the condition passed from dog to dog?

Some forms of Alexander disease in dogs are autosomal dominant, which means that a dog needs only to inherit the gene mutation for the condition from one of their parents to develop the condition themselves. However, the type of Alexander disease Labrador retrievers have increased risk factors for is passed from dog to dog by means of autosomal recessive heredity, which is rather different.

Autosomal recessive heredity means that inheriting one copy of the gene fault that causes the condition is not enough on its own to cause the condition to develop; instead, it depends upon the gene combination inherited from both sides of the dog’s parentage.

Autosomal recessive heredity means that the status of any given litter of pups can be found out by knowing the status of their parents, as follows:

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

DNA testing for leukodystrophy or Alexander disease in Labrador retrievers

Within the UK, there is a DNA testing scheme in place that allows Labrador retriever owners to determine the status of their own dogs, and so, to identify their risk factors for the condition. This information can help breeders to ensure that they only mate dogs who will produce an unaffected litter.

If you would like to get your own Labrador tested to find out their status, you will need to ask your vet to take a blood sample or buccal swab from your dog, which is then sent away to an approved DNA testing laboratory who will return a result of the dog’s status.

If you intend to use this information as the basis of a mating match, don’t forget that both parent dogs need to be tested before the risk factors for the litter they would have can be worked out.