PROGRESSIVE RETINAL ATROPHY SHETLAND SHEEPDOG (PRA-SHET)
Progressive Retinal Atrophy (PRA) is a category of disorders where the retinal cells in a dog’s eye degenerate and die eventually leading to complete blindness. A type of PRA specific to Shetland Sheepdogs is due to a mutation in the CNGA1 gene that leads to adult-onset eye disease. Symptoms will typically appear on average around 5 years old but can present anywhere from 2 to 11 years of age. Initial symptoms include vision difficulties in dim light often referred to as night blindness. As the disease progresses, the affected dog will continue to suffer loss of night vision which then progresses to visual deficits in brighter light and can eventually lead to total blindness. It is important to note that not all cases of PRA in Shetland Sheepdogs are caused by this mutation.
- Shetland Sheepdog
A (CLEAR/NORMAL): These dogs have two copies of the normal gene and will neither develop progressive retinal atrophy nor pass this mutation to their offspring.
B (CARRIER/NOT AFFECTED): These dogs have one copy of the normal gene and one copy of the mutation associated with this disease. They will not develop progressive retinal atrophy but will, if bred, pass the mutation to 50% of its offspring, on average.
C (AT RISK/AFFECTED): These dogs have two copies of the mutation associated with this disease and are susceptible to developing progressive retinal atrophy.