Testing for prcd-PRA: Progressive Retinal Atrophy in Dogs
Progressive retinal atrophy, or PRA, is an inherited eye disorder in dogs leading to gradual vision loss and eventual blindness. Among its different forms, prcd-PRA—standing for progressive rod-cone degeneration—is a particularly prevalent genetic variant responsible for blindness in several dog breeds.
While prcd-PRA does not cause pain, the blindness it causes profoundly affects a dog's quality of life. Because this condition is hereditary and passed down through genes, responsible breeders now routinely test prospective breeding dogs for prcd-PRA to reduce its spread and protect future generations.
The British Veterinary Association and The Kennel Club promote awareness and testing schemes for prcd-PRA, particularly targeting breeds more susceptible to this condition.
What is prcd-PRA Progressive Retinal Atrophy?
Prcd-PRA is a genetic disorder where the rods and cones of the retina—the cells that detect light and colour—degenerate over time. Dogs usually have normal vision at birth, but starting often around three to five years of age, the photoreceptors steadily die, causing night blindness first, followed by complete vision loss.
This form of PRA is caused by a specific mutation known as c.5G>A in the PRCD gene. It is important to note that there are many types of PRA, each with distinct genetic markers, so a test for prcd-PRA specifically detects this mutation only.
Which Dog Breeds Are Prone to prcd-PRA?
Prcd-PRA affects many breeds, particularly those with known genetic predispositions. Commonly affected breeds include the Labrador retriever puppies, Labradoodle puppies, Golden retriever puppies, Poodle puppies, and Cocker spaniel puppies.
Mixed or hybrid breeds like Labradoodles are also at risk if they inherit genes from affected breeds. Potential puppy owners or breeders should consult The Kennel Club’s breeding health database here to check breed health risks. However, non-pedigree dogs may not have fully documented hereditary data.
How Is prcd-PRA Inherited?
The prcd-PRA mutation is inherited as an autosomal recessive trait. This means a dog must inherit two copies of the abnormal gene (one from each parent) to develop the condition and become blind.
Dogs with only one copy are called carriers: they typically show no symptoms but can pass the mutated gene to their offspring. Responsible breeders avoid mating two carriers to prevent affected puppies.
What Are the Signs and Symptoms of prcd-PRA?
Symptoms typically begin with night blindness, where affected dogs struggle to see in low light. The condition progresses slowly, often starting around three years old but sometimes even later, eventually causing total blindness.
Owners may notice their dog becoming hesitant in dimly lit areas or bumping into objects. As the disease progresses, dogs lose their daytime vision too.
How Is Testing for prcd-PRA Done?
Testing involves collecting a DNA sample, usually through a simple, non-invasive cheek swab that your veterinarian can perform. This sample is sent to specialised laboratories that look for the prcd-PRA gene mutation.
The Kennel Club provides a comprehensive list of approved labs here. Many labs also offer home testing kits, allowing owners to collect samples themselves and mail them in.
Understanding Test Results
| Result Type | Genotype | Description | Implications for Offspring |
|---|---|---|---|
| Clear/Normal | N/N | Dog does not carry the mutation | No risk of prcd-PRA from this dog |
| Carrier | N/A | Dog has one copy of the mutation but will not develop the disease | Can pass mutation; breeding with another carrier risks affected puppies |
| Affected | A/A | Dog has two copies of mutation and will develop prcd-PRA | Will pass mutation to all offspring |
Why Is Testing Important for Breeders and Owners?
Testing is vital in helping breeders make informed decisions, avoiding the breeding of two carriers together and thus reducing prcd-PRA prevalence over time. This prevents producing puppies that will suffer blindness.
Owners of at-risk breeds can also benefit from testing to understand their dog's genetic status and prepare for any health changes early.
Additionally, annual veterinary eye exams by a specialist ophthalmologist are recommended to monitor the dog's eye health, as prcd-PRA is only one cause of progressive blindness.
Summary and Next Steps
Progressive retinal atrophy with the prcd-PRA mutation is a serious inherited eye disease leading to blindness in many beloved dog breeds. Genetic testing is a straightforward, non-invasive tool to identify affected dogs and carriers.
By using responsible breeding practices that incorporate testing, the risk of this condition can be steadily reduced, improving canine welfare. If you own or plan to breed a susceptible dog, consult your vet about prcd-PRA testing and work with reputable breeders to ensure healthy puppies.
