# canine hip dysplasia



## Jerry Lyda (Apr 4, 2006)

I was sent the following, what do you think about this?




Breakthrough discovery leads to powerful genetic test 

The challenge was posed nearly forty years ago; the trail has been hot 
for the last two. Long-standing partnerships have resulted in advances 
in diagnosing and understanding hip dysplasia in dogs, a disease that occurs 
when a specific combination of genes exists and results in hip osteoarthritis 
and disability. 

Research indicates that, in addition to Labrador Retrievers, discoveries 
in the diagnosis and treatment of hip dysplasia will assist other breeds 
including Border Collies, Golden Retrievers, Great Danes, Rottweilers, 
German Shepherds and Newfoundland dogs, and has the potential to offer 
insights into similar diseases in other mammals. 

In 2007, with grant support from the Morris Animal Foundation and Pfizer 
Incorporated, Dr. George Lust and colleagues Dr. Rory Todhunter, Steven 
Friedenberg and Dr. Zhiwu Zhang discovered the first panel of genetic markers that could 
lead to genetic testing for the diagnosis of canine hip dysplasia. With 
a new sample of dogs, they plan to verify the accuracy of this panel of 
genetic markers for hip conformation that can predict the breeding value 
of the dog. 

A breakthrough in diagnosis, these genetic tests are expected to be more 
accurate than current procedures, less expensive to perform, and enable 
earlier identification of both normal dogs and those at risk for hip 
dysplasia. Genetic tests may also reduce the need for progeny testing. 

"This has been a long-sought goal," says Dr. Lust. "Now, with one DNA 
sample we are on the road to telling if a young dog will develop 
normally. We will not need to wait until the dog is old enough to 
undergo the current radiographic screening." 

The research team also identified a mutation in the gene for fibrillin 2 
that segregates in a sample of dysplastic dogs and non-dysplastic dogs. 
Fibrillin 2 is a gene expressed in the tissue of hip joints. This is the 
first gene reported to be associated with canine hip dysplasia. The 
discovery opens opportunities for defining the biochemical basis of the disease. 

In other related research, Dr. Lust partnered with Dr. Bernard G. 
Steinetz at the New York University Medical Center to study the 
relationship of two milk-borne hormones---relaxin and estrogen---to the 
onset of hip dysplasia. In a controlled study, the investigators concluded that early 
anti-hormone treatments may be able to negate the effects of the 
milk-borne hormones as they relate to induction of canine hip 
dysplasia. 

More here- 
http://bakerinstitute.vet.cornell.edu/faculty/view.php?id=178


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## Daryl Ehret (Apr 4, 2006)

I wouldn't get terribly excited. They still have to "verify the accuracy" of their genetic markers, which could be overwhelming in number, or beyond any hope of selection against them, before that "could lead to" devising a DNA test for identifying them. Once identified, _then what? _Would there be any examples HD free, to breed upon? And, if so, by narrowing the genepool by overselecting against HD, _different health problems would arise._

Then, there is the matter that only two breeds were even used in their genetic marker study. Other breeds could contain _more or fewer _unrelated markers. Potentially, you could cross two phenotypically healthy dogs that each possess only half any HD related genes, but the same common ones, without worsening the breed population. If you were to breed two phenotypically healthy dogs that each only possess a quarter of the HD related genes, but ones not in common with each other's DNA, who's to say that's any kind of improvement?

In one of his latest published studies (2005), they crossbred 7 greyhounds from racing stock with excellent hip conformation, with 8 Labrador Retrievers with hip dysplasia and secondary hip osteoarthritis, to produce 4 generations of dogs, genotyping 159 of them in 3 generations. This helped them to identify QTL's _believed to be related _to HD (see assumption below) on 12 different chromosomes, each contributing to one or more phenotypes involved, _"as much as 20 to 30 million base pairs and probably as much as 500 to 1,000 genes"._ Also admitting, _"QTL effects are likely to reflect the combined action of multiple linked genes."_

The whole premise was, _"Because of intense selection exerted for racing performance, the Greyhound founders were assumed homozygous for the alleles protective against hip dysplasia. The dysplastic Labrador Retrievers came from a population selected to produce families with dysplastic hips and were assumed to be homozygous at the loci contributing to hip dysplasia."_

They have to publish, to claim that progress is being made, to receive any grant funding. The Baker Institute for Animal Health, appearantly hasn't published a single paper since 2006, so appearantly they're due.


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## Bob Scott (Mar 30, 2006)

Very interesting!
My 5+ yr old GSD Thunder has Moderate HD but shows absolutely no signs of it. 
Trooper will be getting xrayed in a month of two (he's 23 months old). I get a queazy stomach just thinking about Trooper's results.
Something I'd love to see in these studies id if they can discover why some dogs with bad hips on film never show a problem and other dogs with very mild HD on film have to be PTS because of pain. That's got to be some kind of genetic connection.


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## Alyssa Myracle (Aug 4, 2008)

Dr. _LUST... :lol: _


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## Gillian Schuler (Apr 12, 2008)

Bob, I'm no medic but according to my vet, each HD X-ray tells a different story, breed, muscle development, puppy development such as forced to walk too far, etc. etc. etc.

The pain, as I understand it, is caused by arthrotic conditions - if these do not appear - the pain can remain dormant?

I think, from experience, the pain shows up at about 6 years at the latest, depending on the severity. Dogs with good muscles are at an advantage.

Jumps, Schuthund (maybe) is out. I wouldn't like to give out a rule. Watch your dog and decide for yourself.

We have working GSD pedigrees over here that let us assume our pups won't have it, truly. My vet commended me on my dog's hips.


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## Daryl Ehret (Apr 4, 2006)

The concept behind QTL mapping is aimed at identifying inheritance patterns (genetic markers) of chromosomal regions. Outside of that, environmental and other inherited cross-affecting genetic factors _are still important themselves_ in the severity of affects these genes play in the role of CHD.

Also, the many methods of diagnosis themselves (SV,OFA,PENN) can also be found inconsistent, even under their own criteria, and inconsistent in reflecting symptoms of the affected dog.

Another point that should be made, is that the QTL genetic mapping method or the whole concept of Quatnitative Genetics itself has persuasively been argued by some scientists to be less consistently accurate than if selection were made by outward phenotype alone, "the old fashioned way".

But even if ALL the appearant genetic markers related to CHD were clearly identified TODAY, as widespread and multifaceted as the problem appears to be, a planned control strategy for boldly "eradicating" the condition from a breed, is about as easily done as attaining "world peace". Which means, despite the incredible speed and advancement technology has made in recent years, that dream could probably not be realized in our lifetimes.


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## Bob Scott (Mar 30, 2006)

It's also mentioned in the book "Dogs" by Raymond Coplenger (sp) that eliminating a dog from the breed pool based only on HD could very well be eliminating some good genetics. 
Before xray how many "good" dogs with bad hips were bred and nobody gave it any concern.
Just a thought!


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