I just read an interesting article by the President of OptiGen, J.S. Felix, Ph.D. Although it doesn't give the figures requested in the previous thread, it claims that the toal number of Labs tested for prcd-PRA continues to rise annually with Europe accounting for 36%, North America for 60% and others for 4%. The percentage of affected (2%), carriers (23%) and clear (75%) are the same worldwide.

The number of affecteds and carriers has not decreased from 1999-2006 according to their statistics - probably because the number of breeders using this tool remains too low. The graphs showing testing from 1999-2006 were revealing: In Europe, there was a small rise in 2000, then a fall followed by stagnation until 2005, after which the number of tests shot up in a spectacular manner to remain high in 2006. On the other hand, after a drop in 2001 and 2002, the number of tests in North America rose steadily until 2005, before dropping significantly in 2006.

One sentence left me a bit perplexed: "However, we have record of a few Labrador retrievers wih clinical signs of PRA that do not have the prcd form." This was always my understanding but did not tie in with OptiGen's affirmation on their e-mail results: "So far, the only inherited PRA disease known in dogs of your breed is the prcd form of PRA".

I think these percentages could be affected by the fact that people with dogs that are clear by parentage are not testing those dogs, and therefore, they are not included in the count. That would make the percentage of carrier/affected higher than if every normal/noncarrier were to be included. It is like trying to use the OFA's statistics to see what percentage of labs have elbow or hip dysplasia. They are far from accurate, because when a dog's xrays come back obviously dysplastic, they are rarely submitted to OFA, so they are not included in the count.

Corey - I'm no mathematical wiz but it seems to me that if the number of "clear" were even higher, then the percentage of affected/carriers would be lower.

Isn't that what I said?

"I think these percentages could be affected by the fact that people with dogs that are clear by parentage are not testing those dogs, and therefore, they are not included in the count. That would make the percentage of carrier/affected HIGHER THAN IF every normal/noncarrier were to be included."

By that I meant that by not counting all the clear by parentage dogs, it makes the percentage of carrier/affected dogs higher.

Oh boy, where's that coffee??

There can be dogs with signs of PRA that are not inherited. I've heard of a couple dogs that were initially diagnosed with PRA but the degeneration never progressed. It's thought it may be related to diet or something that the dog was exposed it.