It is definitely confusing! :flwr: The thing is: once you actually know the symptoms, and once vets actually can recognise it (most will endlessly misdiagnose as well as miss most symptoms in mild cases as the dog isn't showing them all the time) -- vets see a lot of cases (mine regularly see them and regularly refer to the local vet school for MRIs). To be fair, expecting vets to properly diagnose SM in dogs is like expecting GPs to properly diagnose SM in humans -- it on average takes humans *years* to get the right diagnosis; even other specialists regularly miss it until they get to a neurologist and get an MRI. Reading human Chiari/SM forums and websites can be really helpful to understand the condition and its implications and difficulties better.
Vets everywhere would be unlikely to see a case of SM outside of a cavalier population (and in the US and Canada, they see relatively few cavaliers at most practices -- many here have found they have the only cavalier seen by the practice) and probably 90% wouldn't recognise it if they did see it. Clare Rusbridge says the cases she sees on average take over two years to finally get a diagnosis.
Probably the majority of dogs with the condition don;t show symptoms or symptoms that stand out from other common behaviours and symptoms in dogs. But for about 70% of us, if we MRI our dogs when they are older, they will have syrinxes. A FOURTH of cavaliers UNDER age 1 had syrinxes, in the 555 cavalier sample of mostly UK breeders' dogs from the largest study. That is a lot of cavaliers with syrinxes at a young age
. A syrinx on its own, regardless of symptoms, would be considered a worrying incidental find by any parent of a child, by contrast. It brings a lot of worry over a lifetime about what might happen.
I refer a lot of people to my own vets when their vets won't believe the dog has SM so won't give a neurology referral. In every case so far the dog has had SM and was diagnosed as symptomatic.
Personal example: I have had 5 cavaliers; three have SM. Two would not be noticeable to most people and was never picked up by any vets they saw but I was sure they had it as I had a more symptomatic dog and recognised the scratching wasn't quite 'normal'. Scanning for research confirmed they had SM. The scratching has grown more obvious over the years but still has never been obvious to even most of my cavalier owning friends.
Neurologists say the worst symptoms for human SM and Chiari patients are regular headaches, often very severe. This is almost impossible to diagnose as a 'symptom' in a dog, meaning there's probably a lot of undiagnosed pain out there with this condition. Some researchers are currently trying to find better ways of diagnosing this type of pain, for this condition in dogs.