Blindness in older Japanese Spitz: Why Proof Matters and How We Move Forward

These are not just scientific questions; they are deeply personal ones. For the owner of a blind dog, the diagnosis carries sadness, frustration, and sometimes blame. But if we want to protect our breed responsibly, we must separate speculation from evidence.

Why proof matters for Blindness in older Japanese Spitz

There are multiple causes of blindness in dogs, especially in older age. Cataracts, glaucoma, retinal detachments, and other degenerative conditions can appear in senior years. Without clinical examination and genetic testing, assumptions about the cause stay speculation—not diagnosis. This documentation includes a DNA test confirming PRA-rcd4. It also includes an ECVO certificate (European College of Veterinary Ophthalmologists) confirming PRA more broadly.

Assumptions without proof don’t just create confusion; they can damage trust among owners, breeders, divide communities, and hinder progress.

The Challenge of PRA Diagnosis

A comprehensive study screening 231 PRA-affected dogs across 36 breeds revealed striking findings:

• Only 56% of clinically diagnosed PRA cases tested positive for any known PRA mutation
• 44% of affected dogs had no identifiable genetic mutation despite clear clinical disease
• At least 15 of 21 breeds with known PRA mutations showed evidence of multiple distinct genetic forms

What this means: Even dogs with confirmed PRA may test negative for known mutations. Conversely, a positive genetic test doesn’t automatically mean clinical disease will develop, especially in late-onset forms.

Why PRA-rcd4 Is Complex

PRA-rcd4 is just one of over 21 identified PRA-causing mutations. The research found unexpected patterns:

• The same mutation appeared in ancestrally unrelated breeds
• Different mutations caused similar symptoms in closely related breeds
• Multiple genetic forms often coexisted within a single breed

This genetic heterogeneity makes diagnosis challenging and underscores why both clinical and genetic evidence are essential.

The Two-Part Evidence Standard

1. DNA Testing

What it does: Identifies whether a dog carries the PRA-rcd4 mutation
What it doesn’t do: Confirm clinical disease or rule out other causes of blindness

Genetic status interpretation:

• Clear/Normal: Two normal gene copies
• Carrier: One normal, one mutated copy (typically unaffected)
• Affected/At-risk: Two mutated copies (high risk but not guaranteed to develop disease)

2. ECVO Eye Examination

What it does: Clinically documents retinal changes, visual function, and specific eye diseases
What it doesn’t do: Identify the genetic cause

An ECVO certificate provides:

• Professional diagnosis of PRA or other eye conditions
• Documentation of disease stage and progression
• Differentiation between PRA and other causes of blindness

Together, these tools create the only reliable evidence linking blindness to PRA-rcd4 specifically.

When Laboratory Results Don’t Make Sense

Reputable laboratories maintain high standards, but errors—though rare—can occur during sample collection, processing, or reporting.

Red Flags to Watch For

• Results contradict known parental genetics (e.g., two clear parents producing an affected puppy)
• Multiple siblings show inconsistent results
• Results conflict with clinical presentation
• Sample collection wasn’t professionally verified

Steps to Take

1. Verify parentage: Request DNA parentage testing to confirm lineage
2. Request a retest: Submit fresh samples to the original lab
3. Seek independent confirmation: Test with a second laboratory
4. Ensure proper identification: Have samples collected by a veterinarian who verifies microchip or tattoo
5. Document everything: Keep all certificates, communications, and veterinary reports together
6. Communicate openly: Share anomalies with the testing laboratory—this helps improve quality assurance

Most laboratories welcome investigation of suspected errors and will work cooperatively to resolve discrepancies.

Personal Experience of Blindness in older Japanese Spitz

I own three Japanese Spitz who went blind from confirmed PRA-rcd4. The experience was heartbreaking, but I have never blamed their breeders. Blame is easy; responsibility is harder—and responsibility is where progress begins.

We can’t change the past. But, we can shape the future by testing living dogs. We can also gather precise data. Additionally, sharing results transparently is crucial. This is the most constructive path ahead and the best way to honor affected dogs like my Strela.

When we test, record, and share results — both good and bad — we create clarity. When we focus on transparency rather than personal attacks, we build a stronger community.

Moving Forward: A Practical Action Plan

For All Japanese Spitz Owners

Test your dogs: PRA-rcd4 testing is widely available, with negotiated discounts for the breed. Every result strengthens our collective understanding. Keep records: Store DNA certificates, ECVO reports, and veterinary documents together for future reference. Share results: Contribute to the global PRA-rcd4 registry. Transparency protects breeding programs and honors affected dogs.

For Owners of Dogs Over 8 Years Old

Seek ECVO examination. Seek ECVO examination if there is a sign of blindness or your have dog affected by PRA-rcd4 mutation. Clinical documentation confirms whether symptoms are noticeable or absent. It provides valuable data about disease penetrable and age of onset.

For Breeders

Test before breeding: Know the genetic status of both parents. Document clinical status: Encourage puppy buyers to report any vision problems and seek proper diagnosis. Make informed decisions: Use both genetic testing and clinical data to guide breeding choices. Keep records: Store DNA certificates, ECVO reports, and veterinary documents together for future reference. Share results: Contribute to the global PRA-rcd4 registry. Transparency protects breeding programs and honors affected dogs.

For Puppy Buyers

Ask questions: Request PRA-rcd4 test results for both parents. Understand risk: Even with testing, some uncertainty remains due to genetic complexity. Accept responsibility: Choosing to purchase from untested parents is a personal decision with consequences you must own.

Honoring the Past, Protecting the Future

Whether historical cases of blindness were caused by PRA-rcd4 or something else may never be known. Without DNA and ECVO documentation, it remains speculation. What we can do is ensure their experience leads to progress.

We give lasting meaning to their stories by testing responsibly. We record and share responsibly. Together, we turn experience into a legacy of protection for the breed.

Key Takeaways

✅ Test early and openly: Each result adds to our understanding
✅ DNA ≠ diagnosis: Combine genetic tests with clinical exams for clarity
✅ Errors are rare but possible: Double-check contradictory results
✅ Transparency helps everyone: Sharing results prevents confusion and protects the breed
✅ Lead by example: Your commitment encourages others to follow

Take Action Today

If you have tested your Japanese Spitz for PRA-rcd4, contribute your results to the global register:  PRA-rcd4 Results Submission Form

Transparency today protects the breed’s future.

Final Thoughts on Responsibility

Testing is ultimately a personal choice, and every breeder must decide for themselves. Likewise, purchasing a puppy from untested parents is your decision and your responsibility. We are all adults who must own the consequences of our choices.

We can’t shift responsibility onto others. We can lead by example by testing our dogs. Sharing results openly will encourage others to do the same.

This is why I deeply appreciate Japanese Spitz club board members. I am grateful to every breeder who chooses to test and publish their results. Their openness moves the entire breed ahead.