PRA(rcd4)

Progressive Retinal Atrophy (PRA) is a well-recognized inherited condition to which many breeds of dogs are predisposed. The condition is characterized by bilateral degeneration of the retina which causes progressive vision loss that culminates in total blindness. There is no treatment for PRA, of which several genetically distinct forms are recognized, each caused by a different mutation in a specific gene. The various forms of PRA are typically breed-specific, with clinically affected dogs of the same breed usually sharing an identical mutation. Clinically affected dogs of different breeds, however, usually have different mutations, although PRA-mutations can be shared by several breeds.

Geneticists at the Animal Health Trust (AHT) have identified a recessive mutation that is associated with the development of PRA in the Gordon Setter. The research has revealed that there are at least two forms of PRA segregating in the Gordon Setter. The DNA test we are offering is for the mutation that causes one of these forms, rcd4; the mutation that causes the additional form has yet to be identified.

Rcd4 is the most common form of PRA among Gordon Setters and the development of this test therefore enables breeders to slowly decrease the frequency of an important form of PRA in their lines. However, because we know that at least one other form of PRA exists within the breed, we cannot guarantee that any dog will not develop PRA, even if they are clear of the rcd4 mutation.

Advice

Research has demonstrated that the frequency of the rcd4 mutation in Gordon Setters is high and as many as 50% of dogs might be carriers. The mutation is recessive which means that all dogs can be bred safely but carriers and genetically affected dogs should only be bred to DNA tested clear dogs. About half the puppies from any litter that has a carrier parent will themselves be carriers and any dogs from such litters that will be used for breeding should themselves be DNA tested prior to breeding so appropriate mates can be selected.

It is advisable for all breeding dogs to have their eyes clinically examined by a veterinary ophthalmologist prior to breeding and throughout their lives so that any cases of PRA caused by additional mutations can be detected and that newly emerging conditions can be identified.