Powerscourt Cocker Spaniels

PRA (Progressive Retinal Atrophy) is an inherited eye disease found in many breeds of dogs with varying ages of onset. 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 results in night blindness gradually leading to total blindness. In Cockers, PRA has a variable age of onset, from as early as 18 months to as late as 7 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 recessive conditions, there are 3 "genetic categories", these are "affected", "normal" & "carriers". "Affected" dogs have two copies of the faulty prcd-PRA gene, one inherited from each parent. "Carriers" have one faulty copy of the prcd-PRA gene, they appear healthy & will never develop the disease, they can't be distinguished from "Normal" dogs by the KC/BVA Eye Testing Scheme. "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.

DNA testing of dogs for prcd-PRA is carried out by OptiGen.

When purchasing a puppy ask whether the parents have been OptiGen tested or are from parents who are genetically prcd-PRA Normal/Clear due to having Normal/Clear parents? If the parents have not been OptiGen tested or are prcd-PRA Normal/Clear, please ensure that at the very least they have been screened by the KC/BVA Eye Testing Scheme.

There is no excuse for not testing breeding stock, if you buy a puppy from parents who are not tested, your puppy runs the risk of going blind!

Visit the Kennel Clubs Dog Genetic Health page for more information about inherited diseases in dogs & in particular for information about prcd-PRA.

For Powerscourt OptiGen results please see our "Health Testing Page" page.

On the 1st June 2005 OptiGen announced that they had at long last found the gene mutation and will cease using the "marker" test.

Dogs tested using the "marker" test will have results prefixed by a letter, A1, B1 & C1. Dogs tested by the mutation test will be Normal/Clear, Carrier & Affected.

A1 = Normal/Clear

B1 = Carrier

C1 = Affected

The OptiGen prcd-PRA test is performed on a small sample of blood from the dog. The DNA is analysed for the gene mutation. The result of the test is a genotype - a fingerprint - that allows separation of dogs into three groups for Cocker Spaniels: - Genotype Normal/Clear, Carrier & Affected.

*Possible results using the OptiGen prcd* test**
Genotype	Risk Group	Significance For Breeding	*Risk of prcd* Disease**
(A1) Homozygous Normal	Normal/Clear	Can be bred to any dog. Will never produce affected pups.	Will never develop prcd- PRA
(B1) Heterozygous	Carrier	Should be bred only to Normal/ Clear to remove risk of producing affected's	Will never develop prcd- PRA
(C1) Homozygous Mutant	Affected	Should be bred only to Normal/ Clear to remove risk of producing affected's	Very high chance of developing prcd- PRA

Prcd-PRA is inherited as a recessive trait. This means a disease gene must be inherited from each parent in order to cause disease in an offspring. A carrier has one disease gene and one normal gene, and is termed “heterozygous” for the disease. A normal dog has no disease gene and is termed “homozygous normal” – both copies of the gene are the same, a dog with two disease genes is termed “homozygous affected” – both copies of the gene are abnormal.

Although prcd-PRA is inherited, it can be avoided in future generations by testing dogs before breeding. Identification of dogs that do not carry disease genes is the key. These "clear" dogs can be bred to any mate - even to a prcd-affected dog which may be a desirable breeding prospect for other reasons.

Normal/Clear (A1) dogs, meaning statistically normal for prcd-PRA will never develop this disease or pass it to any offspring. To date, no known normal/clear (A1) dog has developed prcd-PRA or produced prcd-PRA-affected offspring.

Normal/Clear A/A1 can be bred to any dog
Carrier B/B1 should be bred only to A/A1 (Normal/Carrier)
Affected C/C1 should be bred only to A/A1 (Normal/Carrier)

The test makes it possible to breed from Carriers (B/B1 to B/B1) as long you test any puppies before breeding from them. Don't be afraid of your Carriers (B1´s), they ARE sound and will NEVER develop prcd-PRA - breed on with them in a controlled way i.e. ensure you mate them to a Normal/Clear (A1) partner & then test any pups who will be subsequently bred from.

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