It is 25% of GSDs, whose owners sent them in.
Lots of people never get their dogs x-rayed. As the dog ages, arthritis sets in or not, some dogs can have HD and never have symptoms.
Once they are x-rayed, it costs another 30 bucks or so to send them to the OFA. Pet owners who have a problem and get their dog x-rayed get a diagnosis from their vet and probably wouldn't bother sending them in. People who want to work the dog, or do agility, might x-ray, but getting a rating doesn't mean anything, why pay the extra 30 bucks? And breeders, well, if they look at the x-rays and think they may pass, they will send them in. They are not always going to send them in if they do not pass. Why? If you see it there, what's the point of paying another $30 to get it confirmed by the OFA? It does not mean breeders will use these dogs, just that they are not necessarily going to send in the films.
So it is possible that a good percentage of that 25% are actually films that people hoped would pass, but did not.
In any case, it is not a reliable sample. I think there are more than 4 in 100 GSDs with HD, I just think it is very under-reported.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC