Why Hips & Elbows Every Generation? - Page 2

So you expect your puppy buyers to do more then you are willing to.  "...and if people want to breed, they are to get hips & elbows pre-limbed or certified by ofa or penn-hip..."  What if they get a letter from their vet saying hips look good don't need OFA? 

Trafalgar,
Such studies do exist, and while I do not have the data at my fingertips, I can say that they DO reflect :
(1) Hip production follows roughly the expected trend of better production from parents of better hip status, with the largest drop-off in quality being between Normal and Fast-Normal.
(2) Heritability is far from constant, as breedings of Normal X Normal still produce a significant percentage of sub-Normal progeny.


  The question of heritability has been separately addressed by population geneticists such as Malcolm Willis, and is generally placed at around 40% heritability for a given hip status.
I find this somewhat less useful than other data in terms of controlling this problem, but it is helpful to the understanding of the big picture. 
 

  In my earlier post I expressed confidence in the SV HDZuchtwert program, not to say that it is perfect, but that it takes into account actual production of known breeding stock as well as their close relatives, and is amended throughout the breeding life of a dog to acurately reflect their production capabilities.

   I have no use for pedantry, nor for pointless squabbling, and I do not consider myself an expert on this or any other specialty, but I do make an honest effort to avail myself of all knowledge at my disposal, and share it freely whenever it seems appropriate. Jonah

why certify every generation?
to make sure the dogs you are choosing as breeding partners themselves have good hips and elbows. 

can these dogs pass on bad hips, yes they can.  even generations of OFA's backing a dog does not guarantee a damn thing.  some dogs with wonderful hips produce entire litters with HD or ED. I have been told that OFA's only give you a 25% better chance of getting a pup with good hips.  so whats really the point in wasting money to OFA?  well for one its the best we have at the moment.  it shows the dogs themselves have good hips, not what they are going to produce though. 

I recommend anyone who is serious about breeding to do more research.  go beyond just looking for OFA #'s on a pedigree.  look to see how many progeny, relatives, ancestors ect have also received passing ratings.  it may take hours of research but thats the only way to know if you are breeding sound hips and elbows.

is a passing grade the end all of breeding a dog?  thats a decision each individual breeder has to make for themselves.  as it will be you who are dealing with sick puppies and unhappy clients.

Those hours of research on progeny hip scores are what the SV zuchtwert hip score is supposed to be in a nutshell, Uber Land. Of course, that's only for German dogs which are the kind most people here have.

Look, would you rather have the opinion of radiologists who look at hundreds of radiographs, or the opinion of a non specialist vet who looks at a few dozen?

Gotta go, my pack is howling about something.

Great development on this thread!

Some citing of actual articles we can mull over.

Check out the Kapatkin Mayhew and Smith article entitled Genetic Control of CHD

Look at page 3 - interesting stuff.
The  AG (rate of genetic change from one generation to the next) = the heritability (h2) x the selection pressure. (Selection pressure is is defined as the deviation of the parental mean hip laxity from the population mean laxity.)

The PRAGMATIC implcations of focusing on large AG is dealt with later (see selection pressure and strategy for change on page 4).

Unfortunately THIS article doesn't deal with proving the correlation with xrayed "tightness" (what the rating will be) and the actual impairment of dogs with said degree of laxiity - but - at least it's part of the body of evidence that there are SCIENTIFIC/MATHEMATICAL  models for lowering the incidence of a PARTICULAR disease within a population.

I'm not fully convinced that the authors  can unarguably make the conclusions that they do - but what is more interesting to me - is the proposal  of an alternative to "aggressive" seeking of the most rapid genetic change which would necessitate concentrating on the one issue alone and cause serious concern that the necessary extreme selection would "throw the baby out with the bathwater" or that OTHER deleterious issues would INCREASE among the ensuing generations.

See page - last paragraph for the more moderate approach of only breeding from dogs with a degree of laxity in th better half of the breed. More there - no need to paraphrase here. I've always liked this idea because it leaves people the ability to actually breed for other things while still being part of an overall plan for gradual improvement.

Unfortuately - NONE of this takes in account the need to OPEN the gene pool periodically to outside genetic material - but that's a whole other ball of wax and a different discussion.

The other two article links weren't as good as far as Im concerned - they basically were adverts, imo.

I could go on for ever, but I'm not sure anyone read the links or is even interested in the topic.
But it's great that people are diligent enough to look for evidence that helps back up their notions or beliefs.

regards

Well, I am not going to get into the hip issue as I believe in testing every dog used for breeding but I would like to point out that Skidboot went blind from PRA and it was terribly sad to see him at the end due to that. 

For many dogs, going blind is a major deal.  So while I am not one to throw the baby out with the bathwater when it comes to testing and breeding, I would argue that breeding Skidboot without testing the bitches for PRA, at the very least,  was not beneficial.  Smart with health issues is no better than dumb and healthy in my book.

I like to have as much knowledge at my fingertips that I can when I chose to breed.  That includes health testing, performance and temperment evaluations, and pedigree research among other things.  Knowledge is power to me <shrug>

Just my 2 cents.