Progressive Retinal Atrophy (PRA) is an inherited disease that leads to blindness in dogs. It is inherited in a simple autosomal recessive in most breeds. PRA is a disease of the retina. This tissue contains specialized cells called photoreceptors that convert light into nerve signals. These signals then travel to the brain where they are perceived as vision. The retinal photoreceptors are specialized into rods and cones, for night and day and colour vision respectively. PRA usually affects the rods initially, and then cones in later stages of the disease. Therefore early in the disease, affected dogs have night blindness and in the later part their pupils become dilated even in the day to gather more light, may result in a cataract. Age of onset and the rate of progression of the disease differ between the different breeds of dogs.
Researchers have found the mutation in the canine gene responsible for this disease. The mutation causes the protein produced by the gene to be shorter than usual and thus not functional. This leads to atrophy of the retina and results in blindness. This information paved the way for researchers to develop tests to accurately identify this disease in dogs. Breeders and owners can now know if their dog is affected, a carrier or not affected. This allows them to do selective breeding and prevent PRA in the progeny. This information could also lead to the eradication of the disease in the future.
By: Sebastian Chua
Primary references:
http://www.vetgen.com/canine-ref-pra.html
http://www.netpets.com/dogs/healthspa/pra.html
http://en.wikipedia.org/wiki/Progressive_retinal_atrophy
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