UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory

Hereditary Nasal Parakeratosis


Hereditary Nasal Parakeratosis (HNPK) is a genetic defect caused by a mutation in a gene that regulates differentiation of nose skin cells. The mutation affects specialized cells of the nose resulting in the formation of a crust with cracks over the nasal area of young dogs. Affected dogs are otherwise healthy although leaked fluid tends to accumulate in the cracks.

HNPK is inherited in an autosomal recessive fashion with males and females being equally affected. Dogs with one normal and one affected gene (carriers) show no signs of the disease. Carrier dogs will pass on the affected gene to 50% of their offspring.
The VGL offers a test for HNPK. Genetic testing for the HNPK mutation is recommended for Labrador Retrievers. Labradoodles and other crosses with Labrador Retriever content may also be at risk. The test assists veterinarians with diagnosis of HNPK and helps breeders to identify carriers to avoid breeding these together. Mating of carriers is expected to produce 25% of affected puppies.

Allow 3-6 business days for results.

Results reported as:

N/N No copies of the HNPK mutation detected. Dog is normal
N/H 1 copy of HNPK mutation detected. Dog is a carrier and unaffected. If bred to another carrier, 25% of offspring are predicted to be affected.
H/H 2 copies of HNPK mutation detected. Dog has or will develop nasal parakeratosis


V. Jagannathan, J. Bannoehr, P. Plattet, R. Hauswirth, C. Drogemuller, M. Drogemuller, D. J. Wiener, M. Doherr, M. Owczarek-Lipska, A. Galichet, M. M. Welle, K. Tengvall, K. Bergvall, H. Lohi, S. Rufenacht, M. Linek, M. Paradis, E. J. Muller, P. Roosje, T. Leeb. 2013. A mutation in the SUV39H2 gene in Labrador Retrievers with Hereditary Nasal Parakeratosis (HNPK) provides insights into the epigenetics of keratinocyte differentiation. PLOS Genetics. Oct 9(10)
e1003848. https://doi.org/10.1371/journal.pgen.1003848.

Veterinary Genetics Laboratory, Tel 530-752-2211, Email VGL