PRA 

I am sorry I am not an expert in the antioxidant field and cannot give you any worthy advise here

+Noam Pik Thank u for the reply

Optiglo is one. For the unfortunate pet, if caught early it can delay the worsening of symptoms. Onset of symptoms in my breed (yorkies)for prcdPRA is 3 years and up. Papillions have multiple forms of PRA.

Evaluate all breeding dogs with a product like EMBARK. It's research oriented with 200,000 snps and you own the sample. Collectively you can build a huge bank of information when you pair it with a breed specific survey. It pays for itself in the long run.