Relevance Rating: There is some evidence or research available for these breeds
Hereditary nasal parakeratosis (HNPK) causes the nose to dry out leading to chronic irritation and inflammation of the nasal skin. Dogs develop dry, gray to brown crusts on the surface and edge of the nose, painful cracking and a tendency for infection. Skin color can change from dark to light over time. Age of onset average 6 to 12 months. Although not life-threatening, continuous care is required to manage nasal crusting for the dog's life.
Hereditary nasal parakeratosis (HNPK), an inherited monogenic autosomal recessive skin disorder, leads to crusts and fissures on the nasal planum of Labrador Retrievers... (From Jagannath et al, 2013) Hereditary nasal dermatitis is reported in 14 Labrador Retrievers and 4 Labrador Retriever crosses...The lesions were first noted between 6 and 12 months of age. Histopathological analysis revealed parakeratotic hyperkeratosis, often with marked multifocal accumulation of proteinaceous fluid between keratinocytes within the stratum corneum and superficial stratum spinosum. There was also a sub-basal lymphoplasmacytic infiltration within the superficial dermis...(From Page et al, 2003)
Jagannathan, V., Bannoehr, J., Plattet, P., Hauswirth, R., Drögemüller, C., Drögemüller, M., Wiener, D.J., Doherr, M., Owczarek-Lipska, M., Galichet, A., Welle, M.M., Tengvall, K., Bergvall, K., Lohi, H., Rüfenacht, S., Linek, M., Paradis, M., Müller, E.J., 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 9:e1003848, 2013. Pubmed reference: 24098150. DOI: 10.1371/journal.pgen.1003848.
Bauer, A., Nimmo, J., Newman, R., Brunner, M., Welle, M.M., Jagannathan, V., Leeb, T. : A splice site variant in the SUV39H2 gene in Greyhounds with nasal parakeratosis. Anim Genet :, 2018. Pubmed reference: 29423952. DOI: 10.1111/age.12643.
Page, N., Paradis, M., Lapointe, J.M., Dunstan, R.W. : Hereditary nasal parakeratosis in Labrador Retrievers Veterinary Dermatology 14:103-10, 2003. Pubmed reference: 12662268.