What is PRA-b?
[Progressive Retinal Atrophy](https://seniorpet.org/knowledge/[siamese](https://seniorpet.org/knowledge/breed/siamese "Senior Siamese Cat Health Guide")-cat-progressive-retinal-atrophy "Progressive Retinal Atrophy Guide") Bengal type (PRA-b) is an autosomal recessive inherited condition specific to Bengal cats. It causes progressive degeneration of photoreceptor cells in the retina, leading to eventual blindness.
Genetics of PRA-b
| Status | Genotype | Meaning | |--------|----------|--------| | Normal | N/N | No copies of mutation | | Carrier | N/PRA-b | One copy; unaffected but can pass to offspring | | Affected | PRA-b/PRA-b | Two copies; will develop PRA |Key Statistics & Research Data
Screening of nearly 2,500 Bengal cats across Europe by the Langford Veterinary Diagnostic Laboratory (University of Bristol) revealed an overall PRA-b carrier prevalence of approximately 18%, with carriers identified in most European countries tested (Source: Langford Vets Diagnostic Laboratories, University of Bristol, Molecular Diagnostic Unit).
In the UK and Ireland alone, genetic testing of 1,102 Bengal cats identified 912 as Normal (82.8%), 171 as Carriers (15.5%), and 19 as Affected (1.7%), demonstrating that the mutation remains prevalent in the breeding population (Source: Langford Vets Diagnostic Laboratories, Bengal PRA-b Screening Data).
Clinical signs of PRA-b in Bengal cats typically become evident between 8 and 20 weeks of age, with complete retinal degeneration apparent in most affected cats by approximately one year of age, making this an early-onset form of progressive retinal atrophy (Source: Ofri R et al., "Characterization of an early-onset, autosomal recessive, progressive retinal degeneration in Bengal cats," Investigative Ophthalmology & Visual Science, 2015).
PRA-b is inherited as an autosomal recessive trait, meaning that two copies of the defective gene are required to produce clinical disease; carrier cats (heterozygous) have completely normal vision but can pass the mutation to 50% of their offspring when bred to another carrier (Source: Langford Vets, University of Bristol).
Breeding two carrier cats together has a 25% probability of producing affected kittens, a 50% probability of producing more carriers, and only a 25% probability of producing genetically normal kittens, underscoring the importance of genetic testing before breeding decisions (Source: Langford Vets, University of Bristol, Breeding Recommendations).
Age of Onset and Progression
| Stage | Timeline | Signs | |-------|----------|-------| | Early | 2-5 years (or later) | Slight hesitation in dim light | | Moderate | Variable | Bumping into objects in low light, dilated pupils | | Advanced | Progressive | Complete blindness in all lighting | | Late-onset form | 8-12+ years | Slower progression, may not reach complete blindness |
Detection in Senior Bengals
Senior Bengals with late-onset PRA-b may show:
- Reluctance to jump to familiar spots (especially in dim rooms)
- Startling when approached from the side
- Dilated pupils that respond slowly to light
- Changes in play behavior (missing toys, preferring sound-based toys)
- Increased vocalization (calling for orientation)
Diagnosis
| Method | Details | |--------|--------| | DNA test | Definitive; identifies N/N, N/PRA-b, or PRA-b/PRA-b | | Ophthalmoscopy | Retinal changes visible in moderate-advanced stages | | ERG (Electroretinography) | Detects reduced retinal function before visible changes | | Behavioral assessment | Obstacle course in dim lighting |
Managing a Blind Senior Bengal
Environmental Adaptations
- Keep furniture layout consistent — never rearrange without gradual introduction
- Use textured mats/rugs as tactile landmarks
- Add scent markers (vanilla, lavender) at key locations
- Install night lights in hallways (helps cats with partial vision)
- Block access to stairs and balconies with baby gates
- Use water fountains (sound helps orientation)
Enrichment for Blind Bengals
- Crinkle balls and bell toys (sound-based play)
- Puzzle feeders with scent cues
- Catnip trails for exploration
- Gentle interactive play with verbal cues
- Companion cat (sighted) can serve as guide
Key Takeaways
- PRA-b is Bengal-specific and can be definitively identified through DNA testing
- Late-onset forms exist — a senior Bengal can develop PRA-b symptoms even if previously undiagnosed
- Blind Bengals can live excellent quality lives with environmental adaptations
- Never rearrange furniture suddenly in a home with a vision-impaired Bengal
- Sound-based and scent-based enrichment replaces visual stimulation effectively
- All breeding Bengals should be DNA tested for PRA-b to prevent affected kittens