POAG Norwegian Elkhound Type
POAG Norwegian Elkhound Type is a genetic optic neuropathy characterized by an elevated intraocular pressure. Forms of glaucoma can be differentiated as primary or secondary glaucoma. Primary glaucoma is characterized by its onset without any other ocular cause, while secondary glaucoma appears when another cause is present, which triggers glaucoma. Primary glaucoma is one of the most common causes of vision loss in dogs but also humans.
Characteristics and symptoms
Most common characteristic of POAG is an elevated intraocular pressure, which is caused by the blockage of the aqueous humor outflow, as a result of the shallow anterior chamber as well as the obstruction of the iris-trabecular meshwork in the iridocorneal angle of the eye.
In Norwegian Elkhound dog,POAG symptoms usually develop in middle-aged or elderly dogs, but the actual disease onset can be also much earlier. It is common that the peripheral vision is affected as well. With the disease progression, the narrowing of the ciliary cleft is noticed, which contributes to the elevation of the intraocular pressure, and can lead to the subluxation of the lenses as well. As the atrophy of the optic nerve progresses, vision deterioration becomes worse. Retina remains to seem unaffected until the later stages of the disease.
POAG Norwegian Elkhound Type Genetics
Primary opem angle glaucoma in the Norwegian Elkhound is caused by a missense mutation in ADAMTS10 gene. The disorder is inherited as an autosomal recessive disorder. Healthy parents of an affected dog are obligate heterozygotes and therefore carry one mutant allele. Heterozygotes are carriers and show no symptoms. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
Ahonen, S. J., Kaukonen, M., Nussdorfer, F. D., Harman, C. D., Komaromy, A. M. et al (2014): A Novel Missense Mutation in ADAMTS10 in Norwegian Elkhound Primary Glucoma. PloS ONE 9(11): e111941. doi;10.1371/journal.pone.0111941