Quote:
Originally Posted by woland
...this is wrong...HD ever start from genetic heritage...development of the disease for 80% depend on external factors!!
is a big differences!!!!
"...a genetically healthy dog can not get HD disease from external factors.."
i must put bibliografy again?
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Where the bibliografy you send have the hereditability of HD? I only saw an adversiment about it, almost a cultural one for breeders.
Quote:
OBJECTIVE: To determine incidence, risk factors, and heritability estimates of hind limb lameness caused by hip dysplasia in a birth cohort of Boxers. ANIMALS: 1733 Boxers from 325 litters. PROCEDURE: Status of Boxers with respect to clinical signs of canine hip dysplasia (cCHD) was registered during an 8-year period. Survival analysis accounted for dogs lost to follow-up. Effective heritability for developing cCHD was estimated by use of a proportional hazard model on the basis of the Weibull distribution. Parametric survival models were developed to identify the influence of potential risk factors. RESULTS: Cumulative hazard rate for cCHD from 7 weeks to 8 years of age was 8.5%. Dogs that were kept on a floor covered with a slippery material were 1.6 times as likely to develop cCHD, compared with dogs kept on a nonslippery floor. Risk of cCHD doubled in dogs from litters with a high preweaning mortality rate. Dogs that were neutered at 6 months prior to a diagnosis of CHD were 1.5 times as likely to develop cCHD, compared with sexually intact dogs. Dogs >5 years of age were 1.8 times as likely to develop cCHD, compared with younger dogs. Estimated effective heritability of cCHD was 0.11. In terms of the risk of cCHD in progeny, mean estimated breeding value (EBV) of the 10 best and 10 worst sires was -0.32 and 0.42, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Registration of Boxers that develop cCHD may provide a strategy for disease prevention. In addition to diagnostic evaluation of radiographs, sire EBVs provide useful information for breeding selection decisions.
http://www.ncbi.nlm.nih.gov/pubmed/1...?dopt=Abstract
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Its only one studie who shows numbers like that, if you search you will find much more.
I no moment I said HD was not a genetical illness, but the truth is that external factors make a huge difference in the results, of course a dog without genetic for displasy will not show it BUT nothing impeach this dog to have a subluxation because the place it lives or by accident, wrong feed with wrong exercices can cause artritis, all those cases will be considered displasic in the exams, even if those animals have no dysplasi in their genetic, of course we will not see an A dog turn E because it, but we can see non displasic dogs with B or C.
No wonder why we have so many grades for HD.
Yes, the dog cant get displasy by external factors, but he can have artritis and artrosis by it, and it will change the HD evaluation on the official results also as a non displasic dog with bad norberg angles.
In the same way you can get a dog which have a strong genetic for the problem, but because the threatment it will receive B or C.
Well, we have no doubts about how 20 to 30% of genetic can make a huge difference, you can see it principally in the behaviour of working dogs, now you can imagine how much difference it can make when its 40 to 100%.