I think it is important to note that saying a breeder has produced dogs with CM/SM is not a shocking thing. It is the way in which such a comment was intended, that is. And the implication that this is information that would be kept secret by a committed breeder.
It is nearly certain that every breeder produces cavaliers with CM -- the malformation that can cause SM at any time, and for reasons not well understood, and which can cause many of SM's symtpoms on its own (CM is recognised as a separate and equal illness to SM in humans). Indeed it is so hard for researchers to find dogs they agree are totally clear for CM -- the Chiari-like malformation -- that they no longer consider this a meaningful classification when grading MRIs for cavaliers. In other words -- nearly every cavalier is born with a skull that is too small for its brain. Some of these dogs will MRI with syrinxes (SM) as well -- the lowest percentage seen in any random research sample so far is about 40% and on up to 70%. That means that conservatively, probably about half, perhaps slightly less, perhaps quite bit more, of any random group of cavaliers likely has SM. That means 40-70% of the cavaliers owned by people here on CavalierTalk. It's just that it is more likely to be asymptomatic , especially in younger dogs -- but the reality is that it is still there.
That means every breeder has around a 50/50 chance that every puppy bred will go on to develop SM. Fortunately, most dogs with SM at this time do not become symptomatic, but neurologists are seeing far more cases referred to them of early onset, more severe SM with each passing year.
Unless all these dogs are MRId or become clearly symptomatic, it is impossible to know if any breeder's dogs have SM. But the likelihood is that some of them do, or will go on to develop it.
So far, it has been impossible for researchers to find any totally clear lines. This is why research of the type Bruce and so many here helped to fund is very important -- it is helping to indicate some 'more clear' lines, revealing some A grade breeding dogs which are extremely important, and will form the basis of the genome study that hopefully will result in a genetic test for SM in coming years.
The statement that a line produces or has produced SM should not have the stigma attached to it that it currently does because so far, there are NO lines known that DON'T have it. What is needed is more work to ensure that symptomatic cavaliers become rarer and rarer. Breeders already take this attitude towards MVD -- no reputable breeder would insist his or her lines are clear of MVD genes but breeders will breed towards the healthiest hearts possible and the latest onset possible, or no onset. That is what breeders will eventually all want to do with SM as well. Sadly the researchers do not feel SM can ever be eradicated from the breed now -- but it likely can be minimised, just as MVD can be minimised.
To understand what this means -- no clear lines -- consider this. My Leo and Jaspar are from the same, well-known Irish line -- Ronnoc. Their breeder recently passed away, and the dogs from this line have, rather worryingly for the breed, been dispersed to who knows where.
. Some initial probability studies run by an expert computer scientist/statistician in the US on computers indicate Ronnoc is probably one of a tiny handful of more-clear lines -- but only in some distinct subsets. Leo and Jaspar are half brothers, sharing the same father. Jaspar MRI'd a rare clear/clear when a year old (too young for the grading scheme to be considered an A however -- he would need to be re-MRI'd). Leo has moderate grade, symptomatic SM for which he is medicated. Yet the probability work indictates Jaspar's line is the most-clear line within Ronnoc. His half brother is affected. That is how narrow the differences can be, and how important individual MRIs are to probability studies and to finding the genes responsible.
I think all of the above are important distinctions to make. Especially as most breeders that I now of who have MRI'd have been taken aback at the results and find they now need to actively work to breed away from a condition they never thought their dogs had. Only MRIs tell the truth. Breeders need lower cost MRI programs and more support within clubs to MRI -- not the fear of being branded as 'someone who breeds dogs with SM'.
So rather than speak of libellous statements or slander -- which only ensures this subject remains secretive and a source of shame -- let's instead worry about a mindset amongst some breeders where SM is still so taboo that it is an insult to be hurled at others and a way to tarnish a good reputation. Breeders need to move forward and consider how to minimise this affliction, not accuse others of having it. I'd be interested to know if the breeder who made this claim has MRI'd. And if so, what their own results were. icon_nwunsure Until dogs are MRI'd there's no way to know if a breeder's lines have SM, or not.