Cavalier Size and SM

[Brian M]

Hi

Does the physical size of a Cavalier have any bearing on the development of SM ,ie are breed size more susceptible .?
Secondly if not would a larger size Cavalier who developed SM be less affected because they would have a larger skull .? And also do we know if SM is definately an inherited condition and lastly if a Cavalier has been diagnosed with CM do they automatically develop SM .

Sorry if these are questions are going over old ground .

[Holly]

Hi

Does the physical size of a Cavalier have any bearing on the development of SM ,ie are breed size more susceptible .?
Secondly if not would a larger size Cavalier who developed SM be less affected because they would have a larger skull .? And also do we know if SM is definately an inherited condition and lastly if a Cavalier has been diagnosed with CM do they automatically develop SM .

Sorry if these are questions are going over old ground .

Brian-- I'm not an expert and I'm sure others who know more will weigh in, but I don't think actual size of the Cavalier itself has anything to do with it... it's whether there is a malformation of the back of the skull (CM), causing the cerebellum (which should be the shape of a cauliflower floret and "fluffy") to become compressed. This, in turn, puts pressure on the cerebral spinal fluid, which in some cases can cause fluid-filled pockets caused syrinxes (SM).

Is it inherited? I believe they are still trying to isolate the gene (s) causing this...

From my understanding, many more Cavaliers have CM (the malformation of the occipital bone) only (which can cause symptoms but not always) than have SM. Over time, those diagnosed with CM might also develop SM.

Here is a website with pics for comparison that Anne posted in another thread:
http://www.roycroftinformationcenter...l%20Comps.html

That is my very basic understanding and I could have some of this wrong so please feel free to correct me!

[Brian M]

Hi Holly

Regarding point one .If the size of the brain is constant does the larger dog suffer to the same degree if both develop SM as surely the dog with the larger skull can accomodate more readily the same sized brain than the the dog with the smaller skull ,so the larger dog has less intercranial pressure or cerebellar herniation .So would a larger sized Cavalier have a less severe case of SM than a breed standard dog ,therefore are breed standard sizes part of the problem and should larger Cavaliers be more of the norm .

[Holly]

I think it was posted in the BVAC thread under General Discussion that the Foetal Tissue Research is showing that re: larger skulls the cerebellum growth keeps up with the growth of the larger skull size.

[Davecav]

Hi Holly

Regarding point one .If the size of the brain is constant does the larger dog suffer to the same degree if both develop SM as surely the dog with the larger skull can accomodate more readily the same sized brain than the the dog with the smaller skull ,so the larger dog has less intercranial pressure or cerebellar herniation .So would a larger sized Cavalier have a less severe case of SM than a breed standard dog ,therefore are breed standard sizes part of the problem and should larger Cavaliers be more of the norm .

Foetal tissue research has shown that there is a mismatch in the growth of the cavaliers skull v growth of brain, so in terms that I understand this means that when the skull stops growing, the brain continues to grow for a bit longer, instead of what should happen ie: when bones in skull stop growing, the brain should do also.

So to my simple mind - if this is the case, it wouldn't make any difference whether you tried to breed Cavaliers the size of Great Danes, until the faulty genes are found that control the brain/skull growth you would still have the problem of not enough room at the back of the skull - in a much bigger dog. That's how I undertand it anyway.

[anniemac]

I remember Rod did a post in January about some of this. Hopefully with the large grant for the FTR and other research being done by Dr. Rusbridge etc. we will get more information but this is a complex issue. What I remember asking Rod why if the brain is larger is Ella not as smart. I loved his response.

[gamefanz]

Please excuse the possible stupid question but this whole skull thing has me wondering, when does the skull stop growing..age wise? I am really so new at the growth and health of these pups.
Becky

[cavluvver]

My Rossi is large for the breed, 12.7kg and there is no fat on him but he has been diagnosed with sm in April and it is already progressing ie more scratching and face rubbing and he has also had some severe pain episodes, so I don't think size has any bearing on the severity of sm.unfortunately.

[GraciesMom]

I remember Rod did a post in January about some of this. Hopefully with the large grant for the FTR and other research being done by Dr. Rusbridge etc. we will get more information but this is a complex issue. What I remember asking Rod why if the brain is larger is Ella not as smart. I loved his response.

Ells was very smart! She picked you Anne! I do think this is a very good research question since I do think some countries have intentionally breed smaller Cavaliers. There is breeder here who has website advertising smaller dogs "not like the big ones in Europe." This may have had some impact...who knows?

[anniemac]

Ells was very smart! She picked you Anne! I do think this is a very good research question since I do think some countries have intentionally breed smaller Cavaliers. There is breeder here who has website advertising smaller dogs "not like the big ones in Europe." This may have had some impact...who knows?

Advertising smaller cavaliers is a red flag for a byb and to stay away! Some will say 10-12 lbs and people just want a small dog. Nevermind it might end up being 25 lbs! A lot of puppy buyers want a "smaller" cavalier and so they will say this to get people to buy them.

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