Hereditary Nasal Parakeratosis (HNPK)

Description

Hereditary Nasal Parakeratosis (HNPK) is an inherited autosomal recessive disorder in Labrador Retrievers. Autosomal recessive disorders are disorders that can be passed from either parent and require two copies of the gene to show symptoms. A mutation causes the nose to dry out, leading to chronic irritation and inflammation of the nose's skin.

Symptoms of the disorder generally appear around 6 to 12 months of age. Dogs that have a mutation of the Thymine to Guanine (two of four nucleic bases that make up DNA) pairing in the SUV39H2 gene (a gene that codes for enzyme production in DNA) develop symptoms. Symptoms include dry, rough, and gray or brown crusts on the surface and edges of the nose. In some cases, painful cracks appear around and on the tip of the nose. If not treated, affected dogs can develop superficial bacterial infections. Over time, the nose often begins to become depigmented, changing skin color from dark to light in color. Although the disorder is not life-threatening, continuous care to reduce the recurrence of excessive nasal crusting is required throughout the life of the dog.

Because HNPK is a recessive disorder, a dog must have two copies of the mutation in order for the disease to manifest. This means that a dog can have one copy of the mutation and not experience any signs or symptoms of HNPK. This dog would be known as a carrier. The carrier can then pass on either the normal gene or the mutated gene to any offspring. If two carriers are bred, there is a 25% per puppy that they will develop symptoms of HNPK.