Quote:
Originally Posted by Rona
Thanks Marcy 
I suppose this was the element mentioned by the vet radiologist who did the test on Lorka. 
I was wondering - do you think your dog's result become worse because mild HD developed between the first and second tests, or the penhip method was more reliable and showed what the classical tests did not show? |
It's hard to make predictions...PennHip was the first test, which DID NOT show the HD in the standard (OFA) view. I think that test is judged by a panel of 3 vets (blindly), but it might just be one, I'm not sure. OFA films are judged blindly by 3 different vets, with the result being what 2 of 3 diagnose - according to the OFA website, this method has high reliability. There is that "human element" in reading films (which causes a degree of error) which could alter results. And of course, even with PennHip, it requires a human to position the joints. I really, really trust my vets - I have faith that they gave me good films. But again, there is the "human element". I didn't see the 2nd (OFA film), but did see the first (PennHip). Even the examining vet didn't notice any problem with the first, and I (though I am certainly no expert) didn't see anything with the first film either. Roni has definitely changed in structure - more muscle, more filled out, definitely not fat - since 18 months. I think it's quite possible he had a later onset of HD in his left hip. I can only trust that there is a reason OFA requires dogs to be 24 months before they give official results. Since PennHip measures how far the ligament streches (this does not change too much after the age of 4 months, and is hereditary), and OFA looks only for changes as a result of HD - it's a bit difficult to compare the 2 methods.
If it didn't require anethesia, I would do this same "test" of x-raying at 18 and 24 months with all of my dogs...the science is interesting. But, I don't want to put my dogs at risk for my science experiment only.... I only did the OFA films on chance - when I did the PennHip tests, I didn't realize the extent of ED in the breed. I now realize how much it is in our breed - I wanted to do ED tests (which were normal) before I bred, so figured I would do the extra hip films at the same time. The HD results were a surprise, for sure.
PennHip recommends breeding dogs in the "tightest" half of the breed - statistics are recorded after 20 dogs have been PennHip tested for each breed, until then the CSV is compared to "all other breeds". It's almost impossible for a dog with a number <.30 to develop HD. For most breeds .30 -.40 has only a 10-15% chance of developing HD. With a score >.70, it is a very high probability the dog will develop HD. But.....this is all breed specific too. GSDs develop HD at a much lower number than other breeds, as shown by this chart:
http://www.pennhip.org/djdprobability.html
The theory has been this trend is influenced by the "tucked up" structure/movement of the GSD - which we don't have with the CSV! Roni had numbers .38/.39 - pretty low (in the 10-15% range, and better than 80% of dogs of all breeds!). Maybe he was just the unlucky 1 in 10. But, maybe there is something more to the genetics of the GSD (not just the structure) that causes a lower "threshold" - which could also give the CSV the possibility to develop HD even with a "tight" ligament...like I said, the science is interesting - for the CSV and the GSD (a big influence on the CSV genetics). It will be interesting to see how Roni's HD progresses as he gets older - with a low score, hopefully it will stay at mild (C) - but if it gets worse, that also has serious implications for the heredibility at a low number.
Anthea had low (good) scores (.23/.37) and consistently excellent (A1) results, I think she is genuinely healthy, so...I am hopeful this will offset potential problems from Roni in my 4 pups - it seems to frequently be the case with other CSV breeders who have bred parents with A and C hips. Of course the pups will also have x-rays - at 24 months.
It would be cool if the film dates were a part of the database - to compare trends at different ages for HD - if a higher percentage of dogs are diagnosed HD positive at 12, 16, 18, 24, 36 months. As a breeder, I'd really like to have the most reliable results - taken at the most reliable age - to have the best chance to produce healthy results in litters - even if it means waiting 2-3 years to breed.
Marcy