Hip Grading - Page 1

Before it fades into the never-never, can an informed person please pick up thread of How Do You Calculate ZW. Silbersee mentions use of 'template'. Are hip dysplasia gradings arrived at only by overlaying radiograph with some kind of standardised/graded template, or are actual measurements at predetermined locations also taken, and given?

I'm nembie in this game, but I found some info at SV web pages, choose English/American verion. Then Breed Value Accessment HD, there you will find som info about zw/HD and how they calculate. Hope it's what you were looking for. *Jessie*

Cheers Jessie, Thank you very much: I did look there some time back but couldn't quite find the answer. Wish countries would all adopt same system!

Patrishap - One problem is that the OFA and 'a' stamp don't correlate - that the same dog can pass 'a' stamp as fast normal and be mildly dysplastic with OFA , or fast normal or B in Europe and go OFA Good. I know of 3 Belgian and a Danish dogs who are B and C - roughly equivalent to fast normal and NZ, and they went OFA Excellent [B in Belgium] and the rest all went OFA Good. And conversely, fast normal can also go OFA mildly dysplastic. The ZW system is a number based on family PRODUCTION, not a rating of the specific dog's actual hip x-rays. Their rating can affect their ZW, but the intial rating is at birth and an average of the sire and dam. The sire and dam's rating is based on combination of their own hips and hip production of the dog, his sire, dam, their littermates, their other progeny and his littermates, half siblings, and their progeny. I don't understand how they take all the peripherals into account, but the whole family can be affected by a half brothers production. I know a bitch who NEVER produced a litter in Germany, who never had a puppy submitted to the 'a' stamp program and her numbers changed every year - went in 4 years from 89 to 99. Based on hip xrays of dogs produced by her family.

Kougar, what you describe is most likely due to 1) age (hips change as the dog gets older) 2) position of dog while x-ray is taken 3) hormone changes (if female). Yes, I have seen it. A female in heat has a lot more joint laxity (is this the correct word? I am not a native American). I am sure everybody has noticed a female in heat "waddling" around. That is why you never never x-ray a female 4 weeks before, during, and 4 weeks after a heat cycle. Yes, the rating system in other countries is quiet different, and two radiologists have two different opinions. That is why OFA is unpredictable, you have three evaluations and then they take the average. The SV relies on one opinion. Chris

ZW is different than the dogs x-ray reading. OFA and 'a'stamp can be different. If I am buying, I go by worst rating. If I am selling, I go by best! hypothetically of course!

Cheers Kougar, Silbersee and Scotty, I don't pretend to know precise mathematical calculation behind ZW number, but understand principles uunderkying it. Allow me to re-phrase the question. I know the precise measurements, or the scores, for each of my animals. I'm not speaking of the ZW numbers, but the measurements taken from radiograph for each hip. Thus, one particular bitch has total score of two for left hip and three for the right - so, all up, five. I believe average total for UK is 13, here it's slightly less. Here's question: When any of you speak of Normal, Fast Normal or A to E grades, do you also know the underlying actual measurements of each hip? Is their any detailed measuring at all, or is it simply derived more broadly by way of overlaying radiograph with some sort of standardised template as previously mentioned by Silbersee? Put another way: I can say the bitch cited above is Normal, AND that her score is 2,3. Can you do same for your animals?

ahhh - I see now! No - other than Penn Hip which is numerical, I don't have a clue how they critique the x-rays and actual process by which the vets arrive at their decision. I know I have seen some hips I thought were krappy get OK ratings and vice versa. But I am not a vet! Let alone a Board Certified orthopedic vet. Mine are all OFA or 'a' stamped.

I'll add one more factor to Chris' informative list, whether or not the dog being xrayed is tranquilized, anesthesized or done without benefit of any drugs. It will make a difference on SOME dogs. A dog rated fair when xrayed with no meds MIGHT get a mildy dysplastic if under the influence. I've seen it happen. It is more likely to happen in younger dogs where the rating of mildly dysplastic is assigned based on subluxation and shallow sockets, not so much on the remodeling changes seen as the dog ages. I assume the same would hold true for "a" stamps. If you prefer Penn Hip, you know that they cannot do their procedure with a dog that is not under anesthesia as they try to demonstrate as much subluxation as they can and the dog cannot be awake and resisting their efforts. Most of us like to do hips without anesthesia for all the right reasons, but be aware that a relaxed or unconscience dog could demonstrate subluxation you may not see on a wide awake animal and that can make the difference in the rating you receive. If you have a dog that OFA'd fair at a young age and was not tranquilized ot anesthesized at the time and seems to produce a higher percentage of HD than expected, you might want to have another xray done with that dog under anesthesia. It could make a difference.

Scotty, If you're interested in how the radiologists at OFA evaluate the xrays, I believe that information is available on their site or there may be an email addy where you can ask your questions. I know at one time they used a series of measurements including something called the nerburg (sp?) angle and that result was critical in deciding between a fair, a good, and an excellent. Today it all may be done electronically, I don't know. We laypeople often look at what we feel is an excellent xray, deep sockets, well seated round balls, no remodeling, but if that nurberg angle isn't up to par and not what they are looking for in an excellent hip, the dog will get a good or even a fair and we will be disappointed. I've seen maybe 100 hip xrays, many got ratings different than the vets thought they would, and some got numbers when they weren't sure, but they were for the most part giant breeds where the bar is not set as high as it is with GSD's. What is moderately dysplastic in a GSD would be an OFA fair or good for a Saint. Another reason to breed GSD's and not St. Bernards LOL.