Retinal Pigment Epithelial Dystrophy (RPED) in Dogs Explained

Retinal pigment epithelial dystrophy (RPED) is a hereditary eye condition in dogs that affects the retinal pigment epithelium (RPE), a layer of cells at the back of the eye that is essential for maintaining the health and function of the light-sensitive photoreceptor cells (rods and cones). The condition is also known by other names, including central progressive retinal atrophy (CPRA), and is distinct from generalised progressive retinal atrophy (GPRA or PRA), which affects a different layer of retinal cells.

Which Breeds Are Affected?

RPED has been documented in a range of dog breeds, but is particularly associated with the Labrador Retriever, Golden Retriever, Border Collie, Briard, and several spaniel breeds including the Cocker Spaniel and English Springer Spaniel. It has also been reported in some terrier breeds.

Causes of RPED

RPED is an inherited condition. The mode of inheritance varies between breeds; in some breeds it is autosomal recessive (requiring two copies of the abnormal gene for the disease to develop), while in others the inheritance pattern is less clearly defined. The underlying defect involves the abnormal accumulation of lipids within the RPE cells, which interferes with their ability to support the photoreceptors.

Symptoms of RPED in Dogs

Signs of RPED typically develop gradually and may be subtle in the early stages. Common signs include:

• Difficulty seeing in bright light (day blindness or hemeralopia) — this is particularly characteristic of RPED and distinguishes it from GPRA, in which night blindness tends to come first
• Reluctance to go out in bright sunlight
• Bumping into objects in well-lit environments
• Progressive deterioration of vision, which may eventually lead to complete blindness in severe cases

Diagnosis

Diagnosis is made by a veterinary ophthalmologist through ophthalmoscopic examination of the retina. Characteristic pigmented spots or patches on the retinal surface may be visible. Electroretinography (ERG) may be used to assess retinal function in more detail.

Treatment and Management

There is no cure for RPED. Management focuses on supporting the affected dog in adapting to visual loss, minimising additional oxidative damage (some evidence suggests that antioxidant supplementation may slow progression, though this is not definitively proven), and avoiding known risk factors such as excessive vitamin E deficiency. Dogs with RPED can often adapt well to life with reduced vision, particularly if they remain in familiar environments.

Prevention Through Breeding

Testing of breeding stock through ophthalmological examination and, where available, DNA testing helps to reduce the frequency of RPED in affected breeds. Breeders should seek to breed from dogs with clear eye test results.