PRA research

Progressive Retinal Atrophy (PRA)

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Progressive Retinal Atrophy (PRA) is an extremely rare hereditary eye disease that gradually degenerates the retina, ultimately resulting in blindness. This disease was more common many years ago, but has become more and more rare due to research and attentive breeding over the years. This page aims to inform about the disease, breeding recommendations and the research project that was conducted in 2002. Further down you will also find a list of all known PRA carriers.

Generalized Progressive Retinal Atrophy (GPRA) is the form of PRA we have seen in Shelties. GPRA leads to blindness.

Typically the first symptom of GPRA is reduced sight at the age of 3-5 years. The first thing owners usually take note of is reduced night vision or night blindness, followed by decreased reflectivity in the eyes. In certain lighting, the eyes can give off a grey/green or yellow sheen. Blindness usually ensues between the age of 3-8 years. The dog can also develop secondary cataract. There is no treatment for GPRA.

Dogs diagnosed with PRA should undergo a yearly eye exam. It is recommended to take an ERG test (Electroretinography) to confirm or deny the diagnosis, as this is the only way of knowing if the diagnosis is correct or not.

NOTE! Two types of PRA genes have been discovered by researchers (CNGA1-PRA and BBS2-PRA). Both these variants can be proved via blood test. Testing negative for both these types of PRA does NOT mean the dog cannot have other types of PRA. There exists more than these two types of PRA in the breed. However, testing for these variants plays a very important role in weeding out PRA in breeding.

NSSKs breeding recommendations:

• Dogs diagnosed with PRA should not be used for breeding.

• Parents, offspring, siblings or half siblings of dogs with PRA should not be used for breeding (as these are either officially known carriers or offspring of known carriers).

• Dogs with known PRA-carriers on both sides of their pedigree within 5 generations should not be used for breeding.

• Dogs with known PRA-carriers on one side of their pedigree within 5 generations can be used for breeding, but they need to have had a valid eye exam within the last year