Dayblindness, or hemeralopia, was first reported in the Alaskan Malamute in the 1960's. It is a condition also known as "cone degeneration" or "achromatopsia" (ACHM) in man. This condition is now also recognized in the German Short-haired Pointer (GSP). It is essentially a degenerative condition of the "cones" or "bright-light, color" photoreceptors (sensors) in the retina of the eye, which is rapidly progressive and visual problems are evident at a very young age, if one is looking for them. Dogs with dayblindness cannot see in daylight or bright light conditions because the cones (photoreceptors which function in bright light and see colors) are destroyed. The remaining "rods" (dim-light photoreceptors) cannot function in bright light as they are "burnt-out", so the dog simply cannot see, i.e. is functionally blind. Problems are only seen in bright light conditions and not in dim lighting when the dog can cope very well since, in dim lighting, the cones do not function due to lack of light and it is the rods ("black & white" or "light and dark" photoreceptors) which are responsible for detecting the environment (which is why in very dim light you can only see in shades of grey - try it). The cone degeneration cannot be seen by a visual inspection of the eye and, therefore, this condition is not included in the CERF list of conditions noted by their ophthalmologists.

This condition has been seen in Malamutes in the USA ^{(1, 2)}, Canada ^{(1, 2)}, England ⁽³⁾, and in Australia ⁽⁴⁾.

Thanks to the early work of Dr. Kenneth Bourns of Boru Kennels in the early to mid-1960's, the hereditary nature of the condition was discovered. Through their work with the OVC in Guelph, Canada, it was found to be a simple, autosomal recessive condition ^{(1, 2)}. It is now known to be a recessive condition in both man and in GSP as well.

Further extensive work on this condition by researchers at Cornell University in NY (notably Dr. Greg Acland and Dr. Gus Aguirre) has been performed in both man and dogs. The chromosome and the gene(s) responsible for this condition are now characterized in man, Alaskan Malamute-derived dogs (AMD) and GSP. One form of the condition in man (seen on the island of Pingela) and the condition in GSP and AMD are related to the same gene. This gene is called ACHM3 in man and CNGB3 in dogs ⁽⁵⁾. Interestingly, it seems there is a different mutation of the gene responsible in GSP and AMD ⁽⁶⁾.

In the 1960's, when the condition was first recognized in Malamutes, diagnosis of this condition was based purely on clinical signs. However, these can be subtle in some conditions, in some dogs. Signs of a vision problem can be seen as early as 7 weeks of age. No changes are visible on visual examination of the eye by an ophthalmologist, however visual inspection of the eye will help to rule out other causes of loss of vision such as congenital defects, traumatic lesions (including subretinal haemorrhage or retinal detachment) or progressive retinal atrophy (PRA). Later, as technological advances were made in ophthalmologic testing, ERG's (ElectroRetinoGrams) were performed on affected dogs and a characteristic pattern was seen. This is now considered to be "the" clinical diagnostic test for the condition. However, this must be performed under general anesthesia to remove artefacts and keep the dog still during the testing, and analysis of the ERG trace requires specialist knowledge.

Cornell University have developed a DNA test for GSP (available through Optigen) that will differentiate normal, carrier and affected dogs in this breed, but the same test will only definitively detect affected or not-affected dogs in the Alaskan Malamute so, currently, it is not possible to tell normal from carrier Malamutes using the available DNA test. However, the test will confirm an affected dog. Dr. Acland is not optimistic about a more definitive test in Malamutes any time soon, unfortunately ⁽⁶⁾.

There is currently no treatment or cure for dayblindness. Use of sunglasses to reduce the light reaching the eye has been suggested and has been said to help some dogs. The only way to help prevent this condition at present is through careful choice of breeding animals to prevent affected dogs being produced.

References

1. The Bourns Test Litters for Dayblindness in Malamutes
   (http://www.canine-genetics.com/bourns.htm)

2. Day Blindness in Alaskan Malamutes
   (http://www.minnesotamalamuteclub.com/dayblind.htm)

3. Book - The History and Management of the Alaskan Malamute by Janet Edmonds (1985)

4. Genetic and Diagnostic Characterization of Day Blindness in Alaskan Malamute Dogs
   (http://www.users.bigpond.com/amcv/Hughes%20Article.htm)

5. Sidjanin DJ, Lowe JK, McElwee JL, Milne BS, Phippen TM, Sargan DR, Aguirre GD, Acland GM, Ostrander EA. Canine CNGB3 mutations establish cone degeneration as orthologous to the human achromatopsia locus ACHM3. Hum Mol Genet. 2002 Aug 1;11(16):1823-33.
   (http://hmg.oupjournals.org/cgi/content/full/11/16/1823)

6. Personal communications, 2001 to 2004.

7. Optigen web site with CD (Cone Degeneration) test for GSP.
   http://www.optigen.com/opt9_test_cd.html