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  1. #1
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    I keep trying to wrap my mind around SM. Sometimes have more questions than necessary .
    In the percents-is this correct or have I gone off.
    Using 100 Cavaliers
    98 will have OH/CM 98%
    30-70 will have syringomelia 30-70%
    Of the 30-70, 60% will be symptomatic (18-42)
    frecklesmom
    Learning new things everyday

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    No, those would be a bit high.

    The lowest number for CM seen in MRI samples is 85% (Geoff Skerritt) and Clare Rusbridge says at least 90%, but the figure is most likely higher given the enormous difficulty they have had in finding cavaliers without CM. One of the reasons a neurologist panel is being convened in the UK is to address issues over whether there is CM on a given scan, as some neurologists are saying there's none whereas others feel that these are not dogs clear of CM. It can be very hard for neurologists less familiar with the malformation to diagnose it. Also the panel will resolve disputes over the readings of scans/grades. It is a fact that researchers were unable to find enough dogs clear of CM to serve as a clear control group for the genome scan in Montreal and had to go to an entirely different breed that also has SM showing up but also has many fully CM/SM-clear dogs and lines (griffons).

    The estimate of 30-70% with SM is correct -- 30% (from the North Carolina study) is actually low as it excluded dogs with what they termed hydromyelia but many other researchers would view that as the start of SM so the division is a little controversial. Add in those dogs and the figure pushes up around 40% but researchers have gone with their conservative 30%. However these were all dogs under 5. Clare Rusbridge had 70% with SM in her initial sample, which included older dogs. However researchers tend to use the minimum percentage as an estimate.

    Clare Rusbridge says of the dogs she sees with SM, 30% are symptomatic I believe -- but I will check that figure. I may be recalling it incorrectly.
    Karlin
    Cavaliers: Jaspar Lily Tansy Libby Mindy
    In memory: Lucy Leo
    Cavalier SM Information site:www.smcavaliers.com

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    Found the reference -- 35% of dogs which MRI with SM show clinical signs:

    http://sm.cavaliertalk.com/diagnosin...infosheet.html

    Recent studies suggest 35% of SM-affected dogs have clinical signs of the condition. The youngest reported dogs with SM have been 12 weeks old. Dogs may be presented at any age although the majority of dogs (approximately 45%) will develop first signs of the disease within the first year of life and approximately 40 % of cases have first signs between 1 and 4 years old. As many as 15% develop signs as mature dogs with the oldest reported case first developing signs of disease aged 6.8 years. Due to the vague nature of signs in some cases and lack of awareness about the disease there is often a considerable time period (mean 1.6 years) between the onset of signs and confirmation of a diagnosis.
    Karlin
    Cavaliers: Jaspar Lily Tansy Libby Mindy
    In memory: Lucy Leo
    Cavalier SM Information site:www.smcavaliers.com

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    Thank you, Karlin . You can find anything

    So, of 100 Cavaliers

    85-90 will have OH/CM 85-90%
    30-70 will have syringomelia 30-70%
    Of the 30-70, 35% will be symptomatic (10.5-24.5)

    Now on to understanding CSF flow
    It would certainly be easier if the human brain and "accessories" were completely understood.

    CORRECTED 11/4/08 thanks,Karlin
    Last edited by frecklesmom; 4th November 2008 at 03:29 PM. Reason: correction
    frecklesmom
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    Thanks for this thread. Very useful and concise information.
    Jan
    Owned by Rufus (B&T) and Piper (Border Terrier) and in loving memory of 12 years of Toby joy (Tri cavalier) - waiting at the rainbow bridge.

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    98 will have OH/CM 98%
    No, 85-90% are the current estimates. Clare Rusbridge uses the figure of a minimum of 90% and possibly higher.
    Karlin
    Cavaliers: Jaspar Lily Tansy Libby Mindy
    In memory: Lucy Leo
    Cavalier SM Information site:www.smcavaliers.com

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    Is it correct that the North Carolina study was only of 59 dogs? Not sure any real conclusions can be based on such a small study.

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    Yes, obviously a single study too isn't a complete picture. But that is only one of many peer reviewed samples and the results there also roughly fit what Geoff Skerritt has seen in his MRI sample of over 1200 cavaliers.

    It is unfortunate that the clubs and KCs have not pushed for nor funded larger studies but all researchers can work with are the samples they are funded for. One of the main US national clubs funded that NC study so it would be worth people asking them why they chose to stick with a sample that size perhaps?

    Each of these studies has not had as its goal, a measure of the rate of affectedness alone, but have tried to get a sense of the affectedness of the sample. Each has had a specific research objective. I would recommend going and actually reading the abstracts for this study. The goal was to better understand CSF flow and its possible relation to syrinx development and pain. The affectedness levels were a byproduct but absolutely consistent with all studies.

    There's a growing list of peer reviewed papers in prominent journals and papers presented at leading vet conferences, in which samples as in NC, were chosen where the majority of dogs showed no clinical signs of SM, but have all returned at minimum, 30% of dogs already with syrinxes -- full blown SM -- even in the NC sample where the dogs were quite young. Every single dog in the NC sample had skull abnormalities for example. The odds of selecting the only 59 cavaliers with abnormalities seems very odd indeed. This study was the first real wake-up call for US breeders because it was funded by their own major national club, and numerous breeders put dogs in for this study on the assumption that they would come back with clear dogs (breeders posting to the L-list over the months of the study made it clear this was their assumption). Most went away with MRIs showing things they did not expect -- at the very least, the documented skull abnormalities, high degree of cerebellar herniation (the brain forced out of the opening into the spinal cord), etc.

    The fact that not a single study has been done that shows LESS that a 30 affected rate, and that these high levels are consistent across every study, suggests these are not isolated quirky pockets. In addition neurologists themselves have seen a steadily rising number of cavaliers, far beyond any other breed, presenting with the pain and discomfort of SM. I have spoken recently to Geoff Skerritt, who has now MRId 1200+ cavalirs, and nearly 9 in 10 he would diagnose with malformation of the skull and cerbellar herniation, with again significant numbers with syrinxes as well. He has stated in a letter that he finds the state of SM in the breed from when he first began working as a neurologist decades ago to be absolutely salarming. He has said his figures for MRIs with that massive sample are right in line with all the others.

    As the KC rightly has noted, exact percentages are not the issue however -- it is the fact that so many dogs are affected. Even the most skeptical breeders that I have come across do not believe the levels are as low as the 1% of the 'health survey' by the KC . Nonetheless, how odd that the KC chooses to use an unscientific, self reporting owners survey done a few years ago in which almost no dogs were MRId as the basis for its accepted percentage, rather than the year after year now of scientific, peer reviewed studies in which enormous levels of affectedness within MRId dogs, mostly with no clinical signs, are repeated over and over? Why might it choose the non-studies rather than the studies, some funded within the clubs, to come up with its lower percentage?.

    It is also worth reading more on the genome study. There are strong indications that the genes are extremely widespread and that breeding must only go forward with extreme care. The genes don't lie. Some 10,000+ pedigrees went into the genome research and hundreds of MRIs of a wide range of dogs. From talking to the researchers I know how difficult it has been to find ANY completely clear cavaliers -- clear of skull malformation/herniation; clear of syrinxes. It was relatively easy to find griffons -- not just individual dogs but entire families and lines -- fully clear of both. I am sure the researchers -- and breeders -- would be thrilled if a single indication could be found that there are whole clear lines of cavaliers and that the research samples over the past decade have all been anomolies, but they have not been able to find them despite a long search now.

    I know neither researchers, nor breeders, feel they havethe luxury right now of finding exact percentages across a huge rage of cavaliers. They are far more concerned with the urgent issue of finding ways of addressing this alarming problem through better breeding practice -- before this is no longer possible to do. None of the geneticists and other researchers who have looked at this issue in this breed are in doubt that there is only a limited timeframe in which it can be addressed.
    Karlin
    Cavaliers: Jaspar Lily Tansy Libby Mindy
    In memory: Lucy Leo
    Cavalier SM Information site:www.smcavaliers.com

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