Progressive Retinal Atrophy (PRA)
Progressive Retinal Atrophy (PRA) in Papillons (PAP-PRA1) is a late onset eye disorder that results in degeneration of a certain type of retinal cell which is important for low light vision. Affected dogs typically present symptoms of poor vision in dim light at approximately 4 to 6 years of age. PAP-PRA1 typically progresses slowly and can result in complete loss of vision. However, symptoms can vary with some affected dogs maintaining their daylight vision for many years and potentially the rest of their life. Ongoing research has shown that PRA in Papillons can be due to additional mutations besides the PAP-PRA1 mutation.
A (CLEAR/NORMAL): These dogs have two copies of the normal gene and will neither develop Papillon PRA Type 1 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 Papillon PRA Type 1 due to this particular mutation and 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 Papillon PRA Type 1 which results in vision impairment in dim light, progressive vision loss and potentially complete blindness.