A Field bred Swedish Labrador has been diagnosed with a new form of PRA. His sire and dam are both tested Optigen A/Normal for prcd-PRA. As the dog is supposed to be hereditary normal for prcd-PRA he was never tested.
But there is no doubt whatsoever that this dog has PRA. The question is: What form of PRA?

The Labrador male, who is 6,5 years old, was examined in December 2010 in Stockholm, Sweden, by Professor Kristina Narfström, who performed an electroretinography, or ERG as we usually know it. Read more about Professor Narfström here: http://www.vmth.missouri.edu/lco/
To be able to verify what form of PRA this is, the dog's blood will be tested by The Swedish University of Agricultural Sciences, SLU, and by Optigen, USA.
In order to gather more information I have been corresponding with both Professor Gus Aguirre, at University of Pennsylvania - and Optigen.
It is a fact that Optigen has seen quite a few isolated cases of non-prcd PRA in the adult Labrador, with varying qualities of PRA diagnosis - not all as solid as in the Swedish case. A couple of years ago Optigen tried to link these cases to common ancestry. However, the attempt came out unsuccessful, but Optigen will most likely have another go.
There is also strong evidence of a non-prcd form of inherited retinal degeneration from two service dog facilities-closed breeding colonies. In those Labradors, the retinal degeneration appears much earlier than in prcd. Advanced retinal degeneration has been seen at a young age (<3 years of age), which is quite a different PRA in clinical presentation than prcd.
Other than those pedigrees, Optigen is not aware of any strong evidence familial pattern of non-prcd PRA occuring in the Labrador. But the fact that the Labrador Retriever is such a popular breed, the opportunity for another type of PRA to be percolating in the background - masked by prcd - is high.
Optigen wishes to emphasize that they take these cases very seriously and that they want to learn about any/all cases of PRA that occur in the breed. Any owners of PRA-affected Labradors should contact Optigen at once. The affected dogs will be tested at no charge through the Free PRA Testing/Research program in order to gain the best understanding and to advance the research.
In using this program, Optigen has been able to identify both new breeds that carry prcd and also found cases where some breeds are carrying more than one type of PRA. In those cases the first thing Optigen does is to determine if there are any other cases from related dogs showing a similar disease. If there is evidence of common ancestry/familial pattern to the disease, Optigen can conclude that another form of inherited PRA besides prcd is likely present in the breed.
For example, in the Golden Retriever who also develop prcd-PRA and is tested for it, not long ago a new PRA-mutation was identified. When the researchers found out that only a handful of the PRA-affected Goldens depended on the prcd mutation, they started to look elsewhere. And as from November 2010, a test for this new Golden Retriever mutation, GR_PRA1, is available in Sweden, thanks to extensive work by research teams from Sweden, UK and USA.
The research has unfortunately also shown that there is probably a third and so far unknown mutation in another gene, that can also cause PRA in the Golden Retriever. This third form occurs at an early age (<5 years of age).
-If another form of PRA is cropping up in the Labrador we want to immediately have samples on hand to study, with the aim of of developing additional PRA tests to prcd as soon as possible, Optigen says.

The Swedish Labrador Club has taken immediate action on the matter and info (only in Swedish) is now published at the LRC website http://www.labradorklubben.se

Oh great.....out of millions of dogs, one individual is found to have this condition and now there's going to be a new panic in some circles. Two years of heated threads will arise because now there's something new for everyone to debate and spend more money on.

What's Optigen going to be charging now?? an arm and two legs??

This is all the more reason that breeders should be taking their business to Optigen because they are the ones that are working on developing or finding new PRA Forms.

Ingen isn't doing anything but taking money, running test, and also has been know to provide inaccurate results to breeders of many breeds not just Labradors. They are not investing in R&D.

No surprise here. My eye doc has cautioned me for years that there are at least three forms of PRA in Labs and the test only identifies one form. That's why it is so important to have regular eye exams, even on the ones tested clear for the one form of PRA.

MWK

My ACVO has seen other forms of PRA as well in Labs. The test for the most common in Labs is for prcd/PRA...which is the Optigen test.

Sort of related question that I've been wondering about...

Is it improper to take an Optigen clear dog for a CERF exam at a clinic, then? He's a retired obedience dog.

Optigen clear dogs should continue to be examined by ophthalmologists. There are so many more things to look for in the eye.

It's particularly important in obedience dogs, IMHO, as changes in performance may be due to changes in eyesight rather than behaviour issues.

First,I hope everyone, mum/dad/dog have all been DNA tested and parentage verified....that would be MY first step especially before posting to general public

Then, was waiting for the PRA genes to surface outside Optigen clears because the test is NOT 100% ACCURATE folks.............AND only covers the 1 type, central

I hope people who have foregone pedigree research and gone to just "breeding clearances" consider this a wake up call...........

Not sure why, but thought we always knew there was more than just one form of PRA ? Thought it was not seen as much in the US ? And yes, Cerf the dogs yearly there are all sorts of eye problems.