Three out of the five cavaliers I have owned have SM.
Two have or had MVD (at last test) -- one died from this condition, and it was a difficult and exhausting illness to deal with for both dog and for me.
SM is a challenge for any owner as even a 'mild' case can swiftly become a serious case -- and you simply never know what will happen. Most cases progress to some degree. SM is costly to diagnose and manage. I think many who think these are illnesses that can be easily managed find the reality is often very different if they end up with a dog diagnosed with either condition.
Those are realities anyone considering the breed needs to carefully digest. For some, the breed is still worth it. For others, the risk is too high. For many of us who have dogs with these conditions, we question if we will ever have this breed again. Many of us decide to, but anyone who has been through these illnesses generally searches far and wide for a health focused, testing breeder as we know the heartbreak that can come with an ill dog, especially when often, these are young dogs.
I do not think it is ever acceptable to justify going to a breeder who cares so little for the breed that they do not properly test --which means every puppy they breed has a far higher likelihood of having these serious illnesses or passing them on to future offspring and thus affects the entire future of the breed, not just the dogs they selfishly breed for personal reward (income or trophies). The percentage of puppies that scan with SM is considerably lower when both parents are scanned and both or one are A graded dogs. There are some previous threads about how the percentages work out but the difference is 75% or more of the puppies in a litter scanning with SM when parent dogs are unscanned or D or F grade, vs 0-25% when parents are A graded dogs.
Simply because dogs can have varying degrees of a serious illness that is endemic in the breed -- as is the case with SM and MVD -- does not mean dogs, even with mild cases, do not lead compromised lives and that owners do not struggle with the illness and end up living with background worry that makes it hard to enjoy their dog. The goal must be to reduce and perhaps someday eliminate these problems that are destroying our breed, at too young an age. Syringomelia is considered one of the most painful conditions in humans and there is every sign that dogs cover their pain and that owners underestimate it in affected dogs (see the new paper out this week, posted by Rod earlier today). Humans get illnesses for a wide range of reasons, but cavaliers get these illnesses because humans continue to breed them into their dogs. Both diseases could be greatly curtailed IF breeders tested properly and IF they used breeding protocols for health.
Going with a cheaper breeder and just buying insurance to compensate cannot be an ethical approach to puppy buying either -- as it just continues to support the very people who contribute most to the serious health issues in the breed. But buying insurance is a must for most owners as either of these conditions can get very expensive.
Researchers have yet to find any line that is not affected by CM/SM or MVD. Any breeder who promotes their lines as clear is either poorly informed about SM (and thus to be avoided) or deliberately misleading (ditto).
The breed is a wonderful breed, but with many serious challenges. Every puppy buyer can make a big step in helping ensure the breed does have a future -- and right now, that is not clear at all -- by supporting testing, health-focused breeders who know the breed.
Or alternatively, support rescue instead and home a rescue dog.