Primary Open Angle Glaucoma (Norwegian Elkhound Type)

Common Symptoms

Primary open angle Glaucoma (Norwegian elkhound type) is an inherited condition of the eye affecting Norwegian elkhounds. Clinical signs of increased eye pressure typically present when dogs are middle-aged but vision deficits may not be noted until older. As the pressure in the eye increases, the eyeball increases in size and is painful. Signs of pain in the eye include excessive blinking, tearing and redness. If left untreated, the increased pressure in the eye leads to optic nerve damage and the gradual loss of vision. Dogs with glaucoma are at risk for lens luxation. Symptoms of lens luxation include excessive blinking, squinting and tearing of the eye. Dislocation of the lens can occur in both the forward and backward position within the eye, but dislocation in the forward position is more common and serious. If not treated immediately, lens dislocation will exasperate the glaucoma and vision loss. Other symptoms may include bulging eyes and cataracts.

Breed-Specific Information for the Norwegian Elkhound

The Mutation of the ADAMTS10 gene associated with primary open angle Glaucoma (Norwegian elkhound type) has been identified in Norwegian elkhounds. Though the exact frequency in the overall Norwegian elkhounds population is unknown, of the 572 Norwegian elkhounds tested in one study, 25.3% were carriers of the mutation and 0.2% were affected.

Testing Tips

Genetic testing of the ADAMTS10 gene in Norwegian elkhounds will reliably determine whether a dog is a genetic Carrier of primary open angle Glaucoma (Norwegian elkhound type). Primary open angle glaucoma (Norwegian elkhound type) 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 ADAMTS10 gene mutation. Reliable genetic testing is important for determining breeding practices. Because symptoms may not appear until adulthood, genetic testing should be performed before breeding. 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. Norwegian elkhounds 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.

References

• Ahonen SJ, Kaukonen M, Nussdorfer FD, Harman CD, Komáromy AM, Lohi H. A novel missense mutation in ADAMTS10 in Norwegian Elkhound primary glaucoma. PLoS One.2014 Nov 5;9(11). [PubMed: 25372548]
• Ekesten B, Bjerkas E, Kongsengen K, Narfstrom K (1997) Primary glaucoma in the Norwegian Elkhound. Veterinary & Comparative Ophthalmology 7: 14–18.
• Oshima Y, Bjerkas E, Peiffer RL Jr. Ocular histopathologic observations in Norwegian Elkhounds with primary open-angle, closed-cleft glaucoma. Vet Ophthalmol. 2004 May-Jun;7(3):185-8. [PubMed: 15091326]