Dog World Article on SM

[Bet]

Could I mention that in this week's DOG WORLD is an Article on SM by Steve Dean ,who is the Veterinary Columnist for DW .

It is really worth a read.

He mentions the recent Veterinary Papers just Published about this Problem,and how Research is tackling the Disease.

He mentions the difficulties that the Researchers are encountering ,but that they don't negate the Association between Chiari Like Malformation and SM ,since there is a 61%chance of a Dog developing Syrinxeswhere CLM exists.

He further quotes from the Paper, that a Chiari Like Malformation of the Skull is a Heavily associated Factor with the Disease.

In the Third Paper he quotes ,that it could be the Relative Size of the Cavalier Brain its'self .

He goes onto say that ,that it could be considered essential to remove Cavaliers with Clinical signs of SM ,but can the Cavalier Breed go further, suggests that MRI Scanning can be a benefit for CKCS Breeding Stock,but that this Disease has to have more Research done ,including on the Genetic Front.



My question is now ,what is causing Cavaliers to have Larger Brains?

[Tania]

I thought fifteen years ago the Cavalier was physically bred smaller, everything reduced in size except their brain. Their brain isn't too large, it is their skull that is too small. That is the way I understand it!

[harleyfarley]

i thought it was the genes that did not communicate with each other, the genes that dictate the size of the brain are from one type of dog and the genes that dictate the skull size from a different type of dog and they dont speak the same language, the skull size is from a lap dog, and the brain size from a toy spaniel (or similair) when they were first breed. Bruxilles griffons are also bred from toy spaniels and share the same problems. so depending on your cavs original ancestors, if they have toy spaniel genes for brain size and skull size they wont have any problem and will be larger dogs, if they have lap dog genes for skull size and brain size they will also be ok. I assume by now there are so many variations and such a mixture thats why there is a variation in size from 5kg to 16 kg.

As for why some dogs with cm has syptoms and other dont, i put that down to the actual difference in brain size and skull size from a slight variation to a vast difference making the malforation larger, i assume a larger malforation allows more fluid into the spine canal which causes problems before i starts to pool and make shrinxes. This is what ive come to assume reading from animal trust sites. di

[RodRussell]

This is from http://cavalierhealth.org/syringomyelia.htm

August 2009: UK researchers find that Cavaliers do not have a proportionately smaller caudal fossa compared to other small breeds, but that the CKCS's brain is comparatively large. They wrote:

"When compared with Labradors, CKCS had proportionately the same volume of parenchyma in their caudal fossa, hence there is a mismatch of volumes with too much parenchyma in a too small caudal fossa causing overcrowding. ... Other small breeds of dogs had a proportionately smaller volume of parenchyma in their caudal fossa which can explain why, despite having a similar sized caudal fossa to CKCS, they do not experience overcrowding. It is hypothesised that through the miniaturisation process of other small dogs, both the cranium and brain are proportionately smaller but in CKCS only the cranium has reduced in volume, hence why there is a higher incidence of CM in CKCS than other small breeds.

"Cavalier King Charles spaniels also had a greater percentage of their cranial fossa filled with parenchyma (cranial fossa parenchyma percentage) compared with small breeds and Labradors which had a similar percentage. Overcrowding in CKCS might therefore occur due to a mismatch in volumes in both the caudal fossa and cranial fossa of the skull, suggesting the cranial fossa is also involved in the pathophysiology of CM."

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A possible cause of CM? In the same 2009 report comparing the cerebral cranium volumes of the CKCS with those of other small breeds and the Labrador retriever, Hannah Cross and Drs. Claire Rusbridge and Rodolfo Cappello conclude:

"The results support mesoderm* insufficiency or craniosynostosis** as the pathogenesis of Chiari-like malformation (CM) in CKCS. It presents evidence for overcrowding of the caudal fossa due to a mismatch of brain parenchyma and fossa volumes as to why CKCS and not other small dogs are affected."

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(*The mesoderm is the middle of the three primary germ cell layers -- the others being ectoderm and endoderm -- in the early stage of an embryo. The mesoderm is responsible for developing various tissues and structures, such as bone, muscle, connective tissue, and the middle layer of the skin. Mesoderm insufficiency during embryology may cause insufficient scope for the mesoderm and ectoderm layers to develop.)

(**Craniosynostosis is the premature closure of the skull's growth plate.)

[Nastya]

There si a neat book by Temple Grandin titled Animals in Translation. She talks a lot about livestock but her ideas can be applied to any animal. She mentions that when farmers breed livestock to get a particular trait (for example leaner pork) they inadvertely activate/enhance other traits. For example breeding for a leaner pig caused the pigs to become more nervous, aloof, and aggressive. While you are enhancing the activation of a particular gene/or set of genes you are also influencing the activation of genes responsible for other traits. Appears that while cavalier was bred to enhance the appearance of particular traits, other traits were activated or enhanced as well (mitral valve, patelas, SM). I definately suggest the book, its an awesome read.

[Charlifarley]

Is this the lady that is Autistic? I heard her give an interview on the radio a couple of years ago and she was really interesting and knowledgeable (sp?).

[Bet]

I am getting a bit lost now, it was said in DW yesterday that a Cavalier with a Big Head was found to have SM ,this was in the Canadian Research, so what Rod is saying,and I hope he sees this, that he sees this. Cavaliers with the Larger Brains , ,is this due to them having certain Genes,and this is what could be causing the Mismatch in Volumes in both the Caudal Fossa and Cranial Fossa of the Skull.

So is this why it's so important for the Genetic Research to succeed in Canada. ?

[RodRussell]

I am getting a bit lost now, it was said in DW yesterday that a Cavalier with a Big Head was found to have SM ,this was in the Canadian Research, so what Rod is saying,and I hope he sees this, that he sees this. Cavaliers with the Larger Brains , ,is this due to them having certain Genes,and this is what could be causing the Mismatch in Volumes in both the Caudal Fossa and Cranial Fossa of the Skull.

So is this why it's so important for the Genetic Research to succeed in Canada. ?

From the recently published articles on CM/SM, particularly the one titled "Comparison of cerebral cranium volumes between cavalier King Charles spaniels with Chiari-like malformation, small breed dogs and Labradors." (referred to as the "Cross Study", due to H. R. Cross being the first-named researcher listed), it appears that the cause of the cerebellum being overcrowed and partially descending into and through the foramen magnum may be due to an excessively oversized cerebellum (or more accurately, cerebellar parenchyma), rather than an undersized caudal fossa.

But, all of this is still theoretical, as only a handful of Cavaliers have been studied for this defect.

Consider that the current definition of "Chiari-like malformation" is "decreased caudal fossa volume with caudal descent of the cerebellum, and often the brainstem, into or though the foramen magnum." "Caudal fossa volume" apparently is not the problem, based upon these studies. Instead, the oversized cerebellar parenchyma is the culprit.

Anyway, if the new studies are on the right track, then we either must re-define "Chiari-like malformation" or use another term to describe the disorder, since the "malformation" is not of the caudal fossa, but of the cerebellar parenchyma. A re-definition could be "increased cerebellar parenchyma volume with caudal descent of the cerebellum, and often the brainstem, into or though the foramen magnum."

The cause is, I strongly suspect, gene-related. According to the Cross Study:

"The results support mesoderm insufficiency or craniosynostosis as the pathogenesis of Chiari-like malformation (CM) in CKCS. It presents evidence for overcrowding of the caudal fossa due to a mismatch of brain parenchyma and fossa volumes as to why CKCS and not other small dogs are affected."

The mesoderm is the middle of the three primary germ cell layers -- the others being ectoderm and endoderm -- in the early stage of an embryo. The mesoderm is responsible for developing various tissues and structures, such as bone, muscle, connective tissue, and the middle layer of the skin. Mesoderm insufficiency during embryology may cause insufficient scope for the mesoderm and ectoderm layers to develop.

Craniosynostosis is the premature closure of the skull's growth plate.

Finally, to answer the question about the Cavalier with the big head having SM, I would think that if the current research is correct, then it would not matter how big the dog's head is, as long as the cerebellar parenchyma is proportionately oversized for the size of the back portion of the dog's skull.

[Bet]

Thanks Rod, Iv'e thought about your Post, so is not the only answer for the Cavalier Breeders to be that they MUST MRI SCAN their Breeding Stock for SM.

What other way is there to go. ?

I notice that the Hard Core of Cavalier Breeders who put up the excuse about the SM Researchers shifting the Goal Posts, so they don't know where they are ,but what does it matter if the Goal Posts are widened, a Cavalier has to be MRI Scanned to find out if they have a Syrinx, a Syrinx denotes SM, so should not be Bred From .Surely it's as simple as that !!

As for the Accredited Breeders Scheme, will that be enough to help the Cavalier Breed have a future, I don't think so, Mandatory Health Testing for the Two Serious Health Problems afflicting Cavaliers, MVD and SM ,has to be enforced for there to be any chance of the Cavaliers have the slightest opportunity og Healthier Lives.

What a terrible thing to have been said on the recent PDE TV Program in Australia by Jemima Harrison,that in Britain every single one of the 12 TOP UK CAVALIER STUD DOGS has been bred out -side of the MVD Breeding Protocols

For instance ,she went onto say ,if that continues you will never address the Early-Onset Heart Disease in the Breed.

Indeed ,in more than 10 years of Heart Testing in the UK ,there has been no improvement ,for me this further statement from Jemima Harrison should be making some Cavalier Breeders be hanging their Heads in Shame, BECAUSE Breeders ignore what their own CLUBS' BEST PRACTICE ADVISES


There are still 50% of Cavaliers with a Heart Murmur at 5 years of age, this was said at the recent UK CKCS CLUB AGM.

Do those Cavalier Breeders who are still hiding their Heads in the Sand about the SM Problem, ( SM PROBLEM --WHAT SM PROBLEM ....This was said 20 years ago about the MVD Problem in our Cavalier Breed) ,in 10 years time still not be willing to MRI Scan their Cavalier Breeding Stock for SM?

I know that one of the excuses given by this Hard Core of Cavalier Breeders who just won't accept that there is a SM Problem in Cavaliers ,is that the Vets are just not seeing the Cavaliers with SM ,what a Blinkered View ,I would think that even one Cavalier suffering from the Pain of SM would be enough to jolt their Consciences about not MRI Scanning ALL THEIR BREEDING STOCK,not just to say ,because they have MRI Scanned a couple of their Cavaliers, OH ,but I do MRI Scan my Cavaliers. !!

[RodRussell]

Bet, I know that many breeders will take issue with you about testing. They will tell you that they test, and that every other responsible breeder tests, and that the only breeders who do not test are the backyard types and the puppy farmer types who are not members of the Cavalier King Charles Spaniel Club of the UK.

But don't forget what the chairman of the UK Cavalier Club wrote, just six months ago:

"There are many members who are still not prepared to health check their breeding stock, and of those who do, it would appear that many would not hesitate to breed from affected animals."

She's not just talking about Cavalier breeders; she's referring to many Cavalier breeders who are members of the UK club! She knows the truth. She knows which closets have the skeletons and where the bodies are buried, etc.