Dominant Progressive Retinal Atrophy (D-PRA) in Dogs: What You Must Know

Dominant progressive retinal atrophy (D-PRA) is an autosomal dominant genetic disease causing gradual degeneration of the retina in specific dog breeds, leading to progressive, painless vision loss that eventually results in blindness.

Unlike other forms of progressive retinal atrophy which are typically recessive (requiring two copies of a mutated gene), D-PRA requires only one copy of the mutated gene for a dog to be affected. This means that an affected parent has a 50% chance of passing the condition to its offspring.

D-PRA has been predominantly identified in bullmastiffs and mastiffs. Dog owners and breeders with these breeds should be especially vigilant, as the condition progresses slowly over a dog's life. Initially, dogs have normal vision but will develop symptoms such as difficulty seeing in dim light (night blindness), reluctance to enter dark areas, dilated pupils, and eventual complete vision loss.

What is Dominant Progressive Retinal Atrophy (D-PRA)?

Progressive retinal atrophy (PRA) describes a group of hereditary eye diseases that cause degeneration of the retina's photoreceptor cells – rods and cones responsible for vision. D-PRA is a dominant form, meaning just one copy of the mutated gene inherited from either parent results in the disease.

In affected dogs, the retina progressively deteriorates, starting with rod cells; this leads to night blindness as the first symptom. Over time, cone cells are also affected, resulting in total blindness.

While vision loss is painless, it can significantly affect a dog's quality of life, necessitating special care and environmental adaptation as sight declines.

Which Dogs are At Risk?

D-PRA has so far been documented almost exclusively in bullmastiffs and mastiffs, including English Mastiffs. This means that owners, breeders, and potential buyers of these breeds should be aware of the risks.

Since D-PRA follows an autosomal dominant inheritance pattern, breeding an affected mastiff or bullmastiff with any other dog not tested can produce affected puppies. Responsible breeding is essential to reducing the prevalence of this condition.

How is D-PRA Inherited and Diagnosed?

D-PRA is not contagious; it is inherited genetically. Autosomal dominant inheritance means a dog only needs one mutated gene copy from an affected parent to develop the disease.

Diagnosis involves comprehensive eye examinations by vets or veterinary ophthalmologists, sometimes including electroretinograms (ERG) to assess retinal function. Genetic testing is invaluable to confirm whether a dog carries the D-PRA mutation.

In the UK, DNA testing involves taking a cheek swab or blood sample at the vet and sending it to an accredited laboratory. Results guide breeders and owners in making informed decisions.

Breeding and Buying Healthy Mastiffs and Bullmastiffs

If you are looking to buy a bullmastiff or mastiff puppy, always ask breeders for evidence of DNA testing for D-PRA in the parent dogs before viewing puppies. Only consider breeders who openly share these health results and breed responsibly to minimise inherited diseases.

Breeders are encouraged to test all breeding stock for D-PRA and avoid using dogs that carry the mutation in any breeding programme. This helps safeguard future generations from inherited blindness.

Questions to Ask Breeders About D-PRA

• Have the parent dogs been DNA tested for D-PRA? Can you show me the results?
• Are any dogs in the kennel known to have D-PRA or related hereditary eye diseases?
• How do you manage breeding to minimise inherited diseases like D-PRA?
• Can you provide references from previous puppy buyers regarding health and eye conditions?

These questions help ensure you engage with responsible breeders who prioritise the health and welfare of their dogs.

Supporting Dogs Affected by D-PRA

Currently, there is no cure for D-PRA or progressive retinal atrophy in dogs. Management focuses on helping visually impaired dogs navigate safely by maintaining familiar environments and routines.

Owners of affected dogs should provide a safe home, avoid rearranging furniture frequently, and assist dogs with guidance and reassurance as their sight diminishes.

Conclusion

Dominant progressive retinal atrophy is a serious hereditary eye condition primarily affecting bullmastiffs and mastiffs in the UK. Understanding its dominant inheritance pattern, symptoms, and diagnosis is vital for owners and breeders.

Responsible breeding, including DNA testing and transparency by breeders, is key to reducing this condition's impact. Prospective buyers should always verify health screening to ensure they bring home a healthy puppy, supporting the welfare of these beloved large breeds.

Learning about and preventing hereditary conditions like D-PRA helps protect dogs' quality of life—and gives families many happy years with their canine companions.