Hereditary nasal parakeratosis is an inherited disease affecting the nose of dogs. Beginning around 6 to 12 months of age, affected dogs develop dry, rough, gray to brown crusts and rarely, painful cracks on the tip of the nose. In some cases, lesions are also present on the haired area around the nose. The noses of affected dogs are prone to superficial bacterial infections and often become depigmented over time. Affected dogs are otherwise healthy. Symptoms often wax and wane in severity over the dog’s life. Though manageable, this disorder requires continuous topical therapy to prevent recurrence of excessive nasal crusting.
Breed-Specific Information for the Australian Labradoodle
Australian Labradoodle is included as a breed susceptible to hereditary nasal parakeratosis because of its close relatedness to the Labrador Retriever, which is known to develop this disease due to Mutation of the SUV39H2 gene. The frequency of the causal mutation in the general Australian Labradoodle population is unknown.
Genetic testing of the SUV39H2 gene in Australian Labradoodles will reliably determine whether a dog is a genetic Carrier of hereditary nasal parakeratosis. Hereditary nasal parakeratosis is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the SUV39H2 gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Australian Labradoodles that are not carriers of the mutation have no increased risk of having affected pups.
There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.
Jagannathan V, Bannoehr J, Plattet P, Hauswirth R, Drogemuller C, Drogemuller M, Weiner DJ, Doherr M, Owczarek-Lipska M, Galichet A, Welle MM, Tengvall K, Bergvall K, Lohi H, Rufenacht S, Linek M, Paradis M, Muller EJ, Roosje P, Leeb T. A mutation in the SUV39H2 gene in Labrador retrievers with hereditary nasal parakeratosis (HNPK) provides insights into the epigenetics of keratinocyte differentiation. PLoS Genet. 2013;9(10):e1003848. doi: 10.1371/journal.pgen.1003848. Epub 2013 Oct 3.
Page N, Paradis M, Lapointe JM, Dunstan RW. Hereditary nasal parakeratosis in Labrador Retrievers. Vet Dermatol. 2003 Apr;14(2):103-10.