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by Ibrahim on 18 December 2012 - 21:12
Very informative, Hundmutter, though not very encouraging. In a post in another current thread a member mentioned that dysplasia comes from or is connected to more than one gene causing various degrees of it, if that is truen then it is more complex than some may imagine and totally eliminating it is not something achievable.
by Hundmutter on 18 December 2012 - 22:12
Yes, that is polygenetic conditions for you! Hips are not the only
case in point ; see discussions on DM and AF for instance.
And only recently an anniuncement was made that ideopathic
epilepsy could depend on a combination of genes, rather than
one.
It IS depressing; but perhaps not hopeless. More is found out
in genetics all the time, there might one day be more of an
answer for us.
case in point ; see discussions on DM and AF for instance.
And only recently an anniuncement was made that ideopathic
epilepsy could depend on a combination of genes, rather than
one.
It IS depressing; but perhaps not hopeless. More is found out
in genetics all the time, there might one day be more of an
answer for us.
by hexe on 19 December 2012 - 03:12
Hundmutter, you lost me here:
"...so HD can appear in dogs that radiographically didn't ought to have it. Or conversely, like in my Vida's case, NOT develop it even where her hip Xrays were ghastly."
The term 'hip dysplasia' is very specific, and if radiographs of a dog's hips show a normal structure to the joint [both fit and formation of the bones], then the dog quite simply does NOT have hip dysplasia. Likewise, a dog that is asymptomatic, but whose x-rays clearly demonstrate that the bones the comprise the joint are abnormally formed and/or fitted, the dog IS dysplastic, regardless of any absence of pain, discomfort or altered gait. The films don't lie, but they also don't alert the dog to the structure of his or her hips, and a dog that has always been kept extremely fit and managed for optimum muscle tone and weight may well not experience any discomfort as a result of even severely dysplastic hips until there's been significant enough degeneration to the bone surfaces to cause such, well into their adult years.
But malformation is malformation, and hip dysplasia isn't caused by poor diet, over- or under-exercising or anything else; it can be exacerbated, to be sure, but if the joint is correctly constructed to begin with, dysplasia is not going to be introduced by any of those environmental or management factors.
"...so HD can appear in dogs that radiographically didn't ought to have it. Or conversely, like in my Vida's case, NOT develop it even where her hip Xrays were ghastly."
The term 'hip dysplasia' is very specific, and if radiographs of a dog's hips show a normal structure to the joint [both fit and formation of the bones], then the dog quite simply does NOT have hip dysplasia. Likewise, a dog that is asymptomatic, but whose x-rays clearly demonstrate that the bones the comprise the joint are abnormally formed and/or fitted, the dog IS dysplastic, regardless of any absence of pain, discomfort or altered gait. The films don't lie, but they also don't alert the dog to the structure of his or her hips, and a dog that has always been kept extremely fit and managed for optimum muscle tone and weight may well not experience any discomfort as a result of even severely dysplastic hips until there's been significant enough degeneration to the bone surfaces to cause such, well into their adult years.
But malformation is malformation, and hip dysplasia isn't caused by poor diet, over- or under-exercising or anything else; it can be exacerbated, to be sure, but if the joint is correctly constructed to begin with, dysplasia is not going to be introduced by any of those environmental or management factors.
by Hundmutter on 19 December 2012 - 08:12
Yes sorry Hexe I was condensing it down; mindful that some people tell me they have difficulty
even starting to 'read' Xrays, they dont know what to look for or what the changes look like. Agree
it reads badly. I think that what you describe about muscle tone & general fitness is why Vida
stayed free of symptoms until she was quite old.
But there is also anecdotal evidence of cases of apparent dysplasia, in that hips get disLOCATED
etc, which have happened in younger dogs that were Xrayed and got passed. Now they actually
might be down to some other reason; but if a ball comes out of a socket to that extent, it probably
shouldn't. PLUS there is the vet professions sometimes tendency to stick quick labels on
causes for symptoms, without full investigation. Sometimes clients end up believing they have dogs
with HD (which of course need expensive replacement surgery
) when actually they may not have
it.
even starting to 'read' Xrays, they dont know what to look for or what the changes look like. Agree
it reads badly. I think that what you describe about muscle tone & general fitness is why Vida
stayed free of symptoms until she was quite old.
But there is also anecdotal evidence of cases of apparent dysplasia, in that hips get disLOCATED
etc, which have happened in younger dogs that were Xrayed and got passed. Now they actually
might be down to some other reason; but if a ball comes out of a socket to that extent, it probably
shouldn't. PLUS there is the vet professions sometimes tendency to stick quick labels on
causes for symptoms, without full investigation. Sometimes clients end up believing they have dogs
with HD (which of course need expensive replacement surgery
) when actually they may not haveit.
by Prager on 19 December 2012 - 20:12
Unfortunately I do not think that it is that simple.
All dogs have genetic predisposition to HD. The only difference is that in different dogs there is different degree of such predisposition.
Next thing I believe that expression of HD is similar as with cancer. For example, you may be genetically predisposed to have cancer, but if you avoid certain environmental condition which are known to trigger such cancer then the probability of cancer is smaller. I, and many others, firmly believe that it is in principle the same with hip dysplasia in dogs. Thus that believe is that there are not just aggravating factors, but there are also environmental triggers for HD. If the predisposition to HD is small then the trigger needs to be big and if the genetic predisposition is big that the trigger can only be small or even non existent.
Thus if the dog is going to get the HD then that depends on a degree of the genetic predisposition and on a degree of environmental triggers.
Example.
A.Example is extreme but is illustrative. ( Cornell university...I believe)
1.2 dogs with high HD were bred. Produced litter which was dysplastic.
2. same 2 dogs were bred again and the pups were kept for I believe 1 year in containment where they could be only sitting. None or almost none of the pups have bad hips.
B.example Bole GG. Rheumatic diseases. In: Sodeman's Pathologic Physiology, 7th edition, WB Saunders, Phila 1985
many studies were done where it is proven that if the dogs were growing fast the probability of bad hips is higher.
C. example Hill MA, Causes of Degenerative joint diseases ( osteoarthrosis) abd dyschondroplaia ( osteochondrosis) in pigs. J Am Vet Med Assoc 1990;197:107-112
Corbelini CN, Krook L, et al Osteochondrosis in fetuses of ewes overfed calcium . Calcif tissue Int 1991; 48:37-45
Richrdson DC, Skeletal diseases of growing dogs : nutritional influences and the role of the diet. . Canine HD symposium, Western vet conf, February 1995. www.gdcconsulting.com.au/gsd/chd1.htm.
and many many other studies.
Over dose or out of proportion to other minerals of calcium will cause bone problems and HD.
and so on.Thus environment most definitely influences if potentially good hips can be made bad like if given too much calcium and vice versa. To say that it is all 100% genetics and nothing else is simply not truth.
Prager Hans
by guddu on 20 December 2012 - 01:12
" If the predisposition to HD is small then the trigger needs to be big and if the genetic predisposition is big that the trigger can only be small or even non existent. "
This is an important statement, which actually supports the argument that proper selection of breeding partners is essential to keep the genetic predisposition low. Perhaps, instead of OFA goood, fair, dysplastic, we will in the near future classify hips using genetics as HD predisposition low, medium and high.
This is an important statement, which actually supports the argument that proper selection of breeding partners is essential to keep the genetic predisposition low. Perhaps, instead of OFA goood, fair, dysplastic, we will in the near future classify hips using genetics as HD predisposition low, medium and high.
by Blitzen on 20 December 2012 - 01:12
I'm glad you understood that, Guddu. I sure didn't.
by aaykay on 20 December 2012 - 08:12
Sorry, but what of Hans' post was confusing, since I read it too and did find it to be a fairly easy read.
The thing of particularly strong interest to me (where the environmental aspect to HD was shown) was the case when the 2 dysplastic dogs, that previously produced almost all dysplastic pups, when bred again, produced no dysplastic pups.....the key variable between the 2 breedings being that the pups in the 2nd litter were maintained in a manner where the environmental factors that could trigger HD, were firmly kept in check, and the genetic HD predisposition of the pups, was seemingly then trumped - resulting in totally HD free pups !
The takeaway being that the environment (the "nurture" part of the nature-nurture equation) plays a big role in triggering HD, which many folks tend to sweep under the carpet or otherwise ignore.
The thing of particularly strong interest to me (where the environmental aspect to HD was shown) was the case when the 2 dysplastic dogs, that previously produced almost all dysplastic pups, when bred again, produced no dysplastic pups.....the key variable between the 2 breedings being that the pups in the 2nd litter were maintained in a manner where the environmental factors that could trigger HD, were firmly kept in check, and the genetic HD predisposition of the pups, was seemingly then trumped - resulting in totally HD free pups !
The takeaway being that the environment (the "nurture" part of the nature-nurture equation) plays a big role in triggering HD, which many folks tend to sweep under the carpet or otherwise ignore.
by aaykay on 20 December 2012 - 08:12
Guddu: Perhaps, instead of OFA goood, fair, dysplastic, we will in the near future classify hips using genetics as HD predisposition low, medium and high.
I think responsible breeders already do this. Even though a dog may be classified as an A2, the HD pre-disposition might be far lower than a different dog that is classified as an A1 from an HD perspective.
For instance, an "A1" HD rated dog with large number of littermates (and uncles, aunts, cousins etc) exhibiting severe HD, versus an A2 rated dog with parents (and uncles, aunts, cousins, siblings etc) being utterly HD-free.........and in this instance, the HD predisposition is far higher in the "A1" dog than the A2 rated dog and so on. Responsible breeders would clearly eschew the A1-rated dog and go with the A2-rated dog in this instance.
I think responsible breeders already do this. Even though a dog may be classified as an A2, the HD pre-disposition might be far lower than a different dog that is classified as an A1 from an HD perspective.
For instance, an "A1" HD rated dog with large number of littermates (and uncles, aunts, cousins etc) exhibiting severe HD, versus an A2 rated dog with parents (and uncles, aunts, cousins, siblings etc) being utterly HD-free.........and in this instance, the HD predisposition is far higher in the "A1" dog than the A2 rated dog and so on. Responsible breeders would clearly eschew the A1-rated dog and go with the A2-rated dog in this instance.
by Aadilah07 on 20 December 2012 - 10:12
Prager quote - Example.
A.Example is extreme but is illustrative. ( Cornell university...I believe)
1.2 dogs with high HD were bred. Produced litter which was dysplastic.
2. same 2 dogs were bred again and the pups were kept for I believe 1 year in containment where they could be only sitting. None or almost none of the pups have bad hips.
aaykay quote - the key variable between the 2 breedings being that the pups in the 2nd litter were maintained in a manner where the environmental factors that could trigger HD, were firmly kept in check, and the genetic HD predisposition of the pups, was seemingly then trumped - resulting in totally HD free pups !
Nowhere in the example does Prager Hans talk about totally HD free pups...let's not make our own conclusions from a mere example...
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