Progressive Retinal Atrophy
Progressive Retinal Atrophy (PRA) is a group of inherited degenerative diseases affecting the photoreceptor cells (rods and cones) of the retina. The condition leads to progressive vision loss, initially affecting night vision and eventually resulting in complete blindness. Multiple genetic mutations have been identified across different breeds.
Symptoms & Signs
- Night blindness (nyctalopia) - earliest sign
- Dilated pupils
- Increased eye shine (tapetal reflectance)
- Reluctance to navigate in dim light
- Bumping into objects in unfamiliar environments
- Progressive loss of day vision
- Eventual complete blindness
Causes & Risk Factors
PRA is caused by inherited genetic mutations that affect photoreceptor development or maintenance. Different breeds carry different mutations (e.g., prcd-PRA, rcd1, rcd3, XLPRA). Most forms are autosomal recessive, meaning both parents must carry the gene.
Diagnosis
Diagnosis involves ophthalmoscopic examination revealing retinal thinning, vascular attenuation, and increased tapetal reflectivity. Electroretinography (ERG) can detect functional changes before visible lesions appear. DNA testing identifies carriers in many breeds.
Treatment
There is currently no cure or effective treatment to halt progression. Antioxidant supplementation may slow degeneration in some forms. Management focuses on environmental adaptation to help blind dogs navigate safely.
Prevention
DNA testing of breeding stock to identify carriers and affected individuals. Responsible breeding programs using clear-by-parentage or DNA-tested clear dogs. Annual eye examinations through schemes like CERF/OFA.
Prognosis
PRA is progressive and irreversible, ultimately leading to blindness. The rate of progression varies by breed and mutation type. Most dogs adapt well to blindness in familiar environments.