PRA (CRD3) Progressive Retinal Atrophy Testing for Glen of Imaal Terrier
Progressive retinal atrophy (PRA) is a hereditary eye disease causing gradual degeneration of the retina, which leads to blindness in affected dogs over time. The CRD3 variant of PRA, known as cone-rod dystrophy 3, primarily affects the Glen of Imaal Terrier breed, making health testing for this condition critical for responsible breeding and pet care.
The disease results from a mutation in the ADAM9 gene and follows an autosomal recessive inheritance pattern. This means a dog must inherit two copies of the mutated gene (one from each parent) to develop PRA (CRD3), while carriers (with one copy) show no symptoms but can pass the mutation to offspring.
What is PRA (CRD3) Progressive Retinal Atrophy?
PRA (CRD3) is a form of progressive retinal degeneration characterised by the loss of cone cells responsible for daylight vision, followed by rod cells that support vision in dim light and darkness. The degeneration initially causes difficulties seeing in bright and low light and progresses to blindness over several years.
Which Dogs Are Prone to PRA (CRD3)?
PRA (CRD3) is largely unique to the Glen of Imaal Terrier puppies and their crossbreeds with some Glen ancestry. Due to the breed specificity, testing breeding stock and dogs with Glen heritage is important to prevent the condition from spreading within the lineage.
Signs and Symptoms to Watch For
Young dogs under three years typically show no symptoms despite the disease progression beginning between 12 and 24 months of age. Early signs include difficulty navigating in dim light or unfamiliar surroundings. As PRA advances, dogs lose visual acuity leading to eventual blindness.
Understanding the Heredity of PRA (CRD3)
The condition is inherited autosomal recessively, meaning a dog needs two copies of the mutated gene to be affected. Dogs with only one mutated gene are carriers and remain healthy but can pass the gene to their puppies. Careful mating decisions can prevent producing affected puppies.
Genetic Testing: How It Works
Testing for PRA (CRD3) involves collecting a DNA sample, commonly by swabbing the inside of your dog's cheek or a small blood sample. This sample is sent to an authorised laboratory for analysis, with results typically returned within 1 to 2 weeks.
Your local vet can take the sample and usually manages the submission to the testing laboratory. The Kennel Club authorises laboratories that offer this genetic screening, aimed at identifying clear, carrier, or affected status of your dog.
Why Testing Matters for Responsible Ownership and Breeding
Testing breeding dogs and those with Glen of Imaal ancestry helps breeders avoid breeding two carriers or affected dogs, reducing PRA's incidence over time. For owners not breeding, understanding your dog’s status helps anticipate future health needs and manage care appropriately.
By supporting health testing initiatives, owners and breeders actively promote the welfare and longevity of the breed, helping maintain healthy populations and preventing avoidable suffering from blindness.
Next Steps: How to Proceed with Testing
- Discuss with your vet scheduling a DNA test for PRA (CRD3) for your Glen of Imaal Terrier or part-bred dog with Glen ancestry.
- Provide the necessary sampling — cheek swab or blood sample — for laboratory submission.
- Await results, which will classify your dog as clear, carrier, or affected.
- Use results to inform any future breeding decisions responsibly and manage your dog’s health expectations.
Adopting informed and responsible health testing practices ensures healthier litters and enhances quality of life for dogs affected by this condition.
