Japanese Spitz PRA-rcd4 Statistics – Genetic Testing Results

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Current Statistics

Notice: List of Dogs with results is available for registered users.

Understanding the Results

• Clear (WT/WT) – The dog does not carry the PRA-rcd4 mutation. It can’t develop this form of PRA and can’t pass it on.
• Carrier (WT/MUT) – The dog carries one copy of the PRA-rcd4 mutation. It will not develop the disease but can pass the mutation to offspring. Safe breeding is possible when paired with a clear.
• Affected (MUT/MUT) – The dog carries two copies of the PRA-rcd4 mutation. It is at risk of developing late-onset PRA, usually after age 10. Should only be bred to clear (if used at all) to avoid producing affected puppies.

Research Notes on Japanese Spitz PRA-rcd4

Japanese Spitz PRA-rcd4 is the currently documented form of progressive retinal atrophy associated with the breed. Progressive retinal atrophy, or PRA, is not one single disease but a group of inherited retinal disorders caused by different genetic variants in different breeds.

In the Japanese Spitz, PRA-rcd4 affects the retina and can eventually lead to blindness. It is a late-onset condition, which means a dog may appear completely normal for years before visible symptoms develop.

What Japanese Spitz PRA-rcd4 does

Japanese Spitz PRA-rcd4 gradually damages the photoreceptor cells of the eye. In practical terms, affected dogs often begin by losing confidence in dim light. Owners may first notice hesitation in dark rooms, uncertainty outside at night, or increased dependence on familiar routes and routines.

As the condition progresses, the loss of night vision is followed by increasing difficulty in daylight. The pace can vary from dog to dog, but the disease is progressive.

How Japanese Spitz PRA-rcd4 is inherited

Japanese Spitz PRA-rcd4 follows an autosomal recessive mode of inheritance. This means a dog must inherit two copies of the mutation to be genetically affected.

A clear dog does not carry the mutation. A carrier has one copy of the mutation and is not expected to become affected on the basis of that result alone. An affected dog has two copies of the mutation and is genetically at risk of developing the disease over time.

This is why DNA testing is so useful. If at least one parent is DNA-tested clear, affected puppies cannot be produced.

Why DNA testing matters

Because Japanese Spitz PRA-rcd4 is late onset, a dog may already have been bred before any clinical signs become visible. DNA testing allows breeders to manage the risk before breeding takes place.

This is the real strength of genetic testing. It does not wait for symptoms. It allows prevention.

In a breed with a relatively small global population, this matters even more. Hidden carrier combinations are the only way affected puppies are produced. Without testing, that risk remains invisible.

DNA results do not replace clinical observation

A DNA result for Japanese Spitz PRA-rcd4 tells us whether a dog is clear, carrier, or genetically affected for this specific known mutation. It does not tell us exactly when symptoms will begin, how quickly they will progress, or whether another eye condition may also be present.

That is why clinical eye examinations still matter, especially for genetically affected dogs and for long-term breed monitoring. DNA testing and clinical follow-up do different jobs. Both are useful.

Why carriers should not simply disappear from breeding

One of the most misunderstood points in breed health work is this: a carrier is not a sick dog.

In a small breed, removing all carriers too quickly can reduce valuable bloodlines, narrow the breeding base, and create new problems while trying to solve one old one. A more sustainable approach is to test dogs, use carriers carefully, breed them only to clears, and avoid producing affected puppies while preserving genetic breadth.

That is not avoidance. It is strategy.

What a clear result does not mean

A clear result for Japanese Spitz PRA-rcd4 means the dog does not carry this specific mutation. It does not mean the dog is guaranteed free from all eye disease, and it does not exclude the possibility that other PRA-related variants could be identified in the future.

For that reason, responsible breed health work should never depend on one result alone. It should combine DNA testing, clinical follow-up, pedigree knowledge, and honest data sharing.

Breeding principle

My view is simple: Japanese Spitz PRA-rcd4 DNA testing should be a minimum scientific requirement in any serious breeding programme.

It is the most reliable way to prevent affected puppies while preserving valuable lines through informed breeding. The goal is not panic. The goal is not mass exclusion. The goal is controlled, transparent, scientifically grounded decision-making.

How to Send Your Results

1. Test your Japanese Spitz for PRA-rcd4 at a recognized genetic lab.
2. Once you get the results, go to our submission form:  Send your results via Google Form
3. Fill in your dog’s details (name, pedigree number or chip ID, sex, parents’ names).
4. Upload the PDF certificate from the lab.
5. Choose whether your dog’s result can be made public or only shared within breeding committees.
6. Send the form. You will get a confirmation email with a link to edit your entry later if needed.

Notice: If your dog is reported as affected by this mutation, and at least 8 years old. Please schedule an ECVO eye examination. Check for clinical signs. Upload the ECVO certificate later or together with the genetic test.

Update Schedule

The statistic will be published 1 time per mount. Please check back for the latest figures.