PRA (Progressive Retinal Atrophy) is an inherited eye disease found in many breeds of dogs with varying ages of onset and with the generalised type (GPRA), blindness will occur as the disease progresses.
There are various types of PRA but the one most commonly seen in Cockers is GPRA (General Progressive Retinal Atrophy) also known as prcd-PRA.
This disease first shows itself as night blindness, i.e. the dog has difficulty seeing in the dark or in low light conditions. The condition worsens so that sight during good light conditions i.e. daylight becomes poor and eventually the dog will become completely blind.
In Cockers, PRA has a variable age of onset (i.e. from when symptoms are noticed), from as early as 18 months to as late as 7 - 9 years.
It is inherited as a simple Autosomal Recessive gene, meaning that a copy of the PRA gene must be inherited from both parents (one defective allele from each parent) for the disease to occur. Carrier animals (those that inherit one defective allele and one normal allele) do not suffer from the disease and never will - they only have one of the two defective alleles - a dog needs two copies to be affected.
As with all Autosomal recessive conditions, there are 3 "genetic categories"; these are: - "normal", "carrier" and "affected".
"Normal" - dogs are entirely free of the prcd-PRA gene, i.e. they have no copies of the gene. They will never develop the disease and neither can they pass it onto their offspring.
"Carriers" - have one faulty copy of the prcd-PRA gene, they appear healthy and will never develop the disease, and they cannot be distinguished from "Normal" dogs by the KC/BVA Eye Testing Scheme. They will never develop prcd-PRA themselves but can pass the gene to their offspring and produce "Carriers" if mated to a "Normal" partner and "affected" if mated to another "Carrier.”
"Affected" - dogs have two copies of the faulty prcd-PRA gene, one inherited from each parent and they are affected with the disease.
Visit our eye disease page for more information about prcd-PRA & other eye diseases.