Chiari-like malformation is found to be progressive

[RodRussell]

UK researchers, including Drs. Rusbridge, Driver, and McGonnell, reported to the ACVIM in a June 2011 study that CM-affected cavaliers' foramen magnums and the length of cerebellar herniation "increased significantly" between MRI scans averaging 9.5 months apart. they concluded:

"This work could suggest that overcrowding of the caudal cranial fossa in conjunction with the movements of cerebrospinal fluid and cerebellar tissue secondary to pulse pressures created during the cardiac cycle causes pressures on the occipital bone. This leads to a resorption of the bone and therefore an increase in caudal cranial fossa and foramen magnum size allowing cerebellar herniation length to increase."

See http://bit.ly/qUJK1F for more details.

[anniemac]

I thought I was going to have a day off but can you please explain in laymans terms? What about mild cm that never develops a syrinx but is symptomatic? Does this have some help with the friend we have?

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[anniemac]

If I'm reading it right that cm doesn't determine presence of sm and other factors? That's something I've wondered about. Do we know if they were symptomatic? I'm asking because so many people feel severity of SM but knowing symptomatic CM cavaliers like Dougal for example

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[RodRussell]

I thought I was going to have a day off but can you please explain in laymans terms? What about mild cm that never develops a syrinx but is symptomatic? Does this have some help with the friend we have?

I think it means that CM can get worse. The foramen magnum -- that hole in the back of the occipital bone of the skull -- actually can get bigger, and as it does, more of the cerebellum can squeeze through.

The researchers' hypothesis is that the over-sized cerebellum, combined with the movements of cerebrospinal fluid and cerebellum during heart beats, cause pressure on the occipital bone. This leads to the bone reducing in size, thereby enlarging the foramen magnum, allowing more of the cerebellum to squeeze through.

That is all I know.

[Tania]

Thank you for explaining this.

[Margaret C]

UK researchers, including Drs. Rusbridge, Driver, and McGonnell, reported to the ACVIM in a June 2011 study that CM-affected cavaliers' foramen magnums and the length of cerebellar herniation "increased significantly" between MRI scans averaging 9.5 months apart. they concluded:

"This work could suggest that overcrowding of the caudal cranial fossa in conjunction with the movements of cerebrospinal fluid and cerebellar tissue secondary to pulse pressures created during the cardiac cycle causes pressures on the occipital bone. This leads to a resorption of the bone and therefore an increase in caudal cranial fossa and foramen magnum size allowing cerebellar herniation length to increase."

See http://bit.ly/qUJK1F for more details.

At the health day last November Dr McGonnell reported that all the cavalier whelps she studied in the Foetal Tissue Research had a suture in the middle of the Supraoccipital bone ( apparently it is unusual to find this within bone ) which appeared to close before birth ( early fusion )

The whelps had less high quality ( weak ) bone, lots of marrow and increased blood cells and they all had disorganised structure and large blood vessels.

http://www.cavaliertalk.com/forums/e...issue-Research

I wonder if this weak bone in the cavalier skull contributes to the reported resorption.

At post-mortem Monty ( Ch. Mareve Indiana ) was found to have a large keyhole shaped foramen magnum.
The hole was partly covered by cartilage and that was possibly the reason his symptoms did not manifest until he was an old man. The cartilage was more flexible and crushed his brain less than the bone that would normally be there.

[Margaret C]

I see this announcement brought the usual reaction from breeders who demand they should be given up-to-date information, but then attacks anything that suggests there really are deep seated health problems in Cavaliers.

An abstract written by leading researchers, including the formerly highly praised head of the Foetal Tissue Research, gives proven facts about 12 cavaliers and suggests what may be happening.

Below is an illustration on how it was received.

In a couple of weeks time the highlighted words and phrases will be parroted by people that have not even read the report..................

Some people are very good at making the bullets for others to fire..........................

"A study conducted on 12 dogs ............ I have faith in the researchers, but find it difficult to accept on those figures that one could make any hard and fast statement, surely?"

"I just find it really difficult to swallow these sweeping statements based on such a small percentage of dogs"

"What I have a problem with it how can you reasonably expect anyone to take as "gospel" something based on 12 dogs.

Hard and fast statement? sweeping statements? gospel?

No, I don't think so. Just a report on a piece of research and a suggestion as to what it may mean.

[anniemac]

Now wait a minute. I don't want to get in the middle of what people say but this topic does hit home. I'm not saying anything about this research because I know it is something we all want. I want to speak for 2 cavaliers and one specifically that is a pet owner just wanting answers. If you haven't read my blog, its funny because I just wrote about this before this came out. It has nothing to do with research. I can't speak for them because I don't know and I don't want to debate on a forum they are not on. You can read my blog www.fightforella.blogspot.com.

They have symptomatic CM cavaliers and bravely spoke out about it. I commend them for it and especially when they are scanning multiple times and helping with research. After the one with symptomatic CM she spent over a year researching getting a new cavalier from 2 fully scanned SM clear parents and even scanned grandparents.

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[RodRussell]

... They have symptomatic CM cavaliers and bravely spoke out about it. I commend them for it and especially when they are scanning multiple times and helping with research. After the one with symptomatic CM she spent over a year researching getting a new cavalier from 2 fully scanned CM/SM clear parents and even scanned grandparents.

I think symptomatic CM cavaliers (which means, the dog does not have SM, and therefore is an "A", but does suffer pain from CM) may be a loophole in the SM breeding protocol. The protocol okays breeding any cavalier which does not have SM. They are the "A" grade cavaliers. I long have suspected that the pain of CM/SM really is the pain of CM alone. I don't recall that any studies have refuted this hunch.

There are CM/SM cavaliers without symptoms, which includes no displays of pain. So it is possible to have SM and not, at least, give outward evidence of pain. And there are non-SM cavaliers, having only CM, which display signs of severe pain. So, why not reason that the pain experienced by CM/SM dogs is due to the CM and not the SM?

Should the SM breeding protocol be revised to ban symptomatic "A" cavaliers? I don't know, because it may be that breeding any "A" is better than breeding no "A" at all. This is a question for the geneticists and the neurologists to answer.

[RodRussell]

I see this announcement brought the usual reaction from breeders who demand they should be given up-to-date information, but then attacks anything that suggests there really are deep seated health problems in Cavaliers. ...

Yes, interesting, isn't it? Thank you for being so concise in your analysis. I could not put my finger on the irony, like you have.