Hereditary Nasal Parakeratosis (HNPK) testing for the Labrador retriever

Hereditary nasal parakeratosis or HNPK for short is a hereditary health condition that has been identified as present in the gene pool of the Labrador retriever breed.

The condition occurs due to a mutation of the SUV39H2 gene, which causes the nose of affected dogs to dry out and be unable to lubricate itself as normal, which leads to chronic inflammation of the skin of the nose that can be very irritating for affected dogs.

Dogs that inherit the condition will usually present with symptoms by the time they reach the age of 6-12 months, and the initial symptoms include rough, dry crusting on the nose and the edges of the nose where it reaches the rest of the muzzle. The crusting is usually grey or brown, and due to the dryness that accompanies the condition, the surface of the nose is also prone to cracking and splitting, leading to painful sores that also run the risk of being very prone to developing infections.

As the condition progresses, the pigmentation of the nose itself will change too, fading from its natural dark colour to a lighter pink shade.

While the condition does not affect the dog’s normal lifespan and compared to many hereditary health conditions, may be thought of as fairly minor in the greater scheme of things, it can still be painful and irritating for affected dogs as well as increasing the risk of them developing infections.

Lifelong maintenance and careful management of the condition is necessary on the part of the dog’s owner in order to preserve the dog’s quality of life.

Because the condition can be passed on from dog to dog by means of heredity, The Kennel Club oversees a screening and monitoring scheme for the condition, to allow Labrador retriever breeders to find out the status of their own dogs before making a decision on whether or not to breed from them.

In this article, we will look at hereditary nasal parakeratosis 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 hereditary nasal parakeratosis

Hereditary nasal parakeratosis is not contagious between dogs, and can only be passed on by means of heredity from parent dogs to their offspring. While the condition is not in and of itself life threatening, it can make affected dogs fairly miserable due to the inflammation and irritation of the nose, and can be painful if the skin of the nose cracks into open sores.

The chances of developing an infection in the sores is high too, which can lead to secondary complications. Hereditary nasal parakeratosis cannot be reversed or cured, and caring for dogs with the condition involves working to keep the nose clean and moisturised, to reduce the accompanying irritation and the chances of sores and cracks developing, which can be hard to treat.

What sort of dogs can be affected by the condition?

In UK dog populations, hereditary nasal parakeratosis has been identified in the Labrador retriever dog breed only, with the onset of symptoms usually beginning at around six months to one year of age.

The condition affects males and females equally, and is not more or less prevalent in either show lines or working lines of Labrador retrievers.

Cross breed dogs with one Labrador parent may inherit one of the two necessary copies of the mutated gene that causes the condition from the Labrador side of their ancestry, and while this may lead to them becoming carriers for the condition, is not enough on its own to lead to the affected form of the condition.

How does the heredity of the condition work?

Hereditary nasal parakeratosis is inherited by means of autosomal recessive modality, which means that in order to develop the affected form of the condition, the dog must inherit two copies of the gene mutation that causes it; one from each parent.

Dogs are referred to as either clear, carrier or affected, and the status of the two parent dogs determines the status of their subsequent litter, as outlined below:

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

How to get your dog tested for hereditary nasal parakeratosis

If you own a Labrador retriever that you are considering breeding from, it is important to get your dog tested for their status before selecting a mating match, and also, to find out the status of their potential match too.

To find out your own dog’s status, you will need to ask your vet to take a DNA sample from your dog and send it off for analysis at one of The Kennel Club’s approved laboratories, who will then return the result of your dog’s status to you.