Welcome to the forum and so sorry you have had this upsetting diagnosis. :flwr:
It is good that you are already aware of what is going on as that gives you more options to think about in terms of treatments over time and also means you can monitor her more carefully and react more quickly, as needed. :flwr:
Have you spoken to the neurologist at all or just your vet? I think you will find speaking to the neurologist will give you a lot more information. On the eye movements -- I would doubt this could be from becoming dizzy due to scratching -- I've never heard of this before -- but nystagmus, or problems with eye movements, are a known symptom of SM in humans and dogs so be sure to discuss this with the neurologist if you haven't (I am sure you probably have) and if she appeared frightened then it was probably related to some pain or lack of coordination connected to that I'd think?
Also I think the rubbing on the neck may be causing the scratching, myself -- those reflex scratches (which most dogs will do
) usually are more due to rubbing bellies or the sides of most dogs, not the top of the neck if that is where you are rubbing. But air scratching in cavaliers really means scratching when upright, not when you stimulate it, so you probably aren't seeing actual air scratching, but maybe a discomfort reaction due to rubbing that area. I really would try to avoid putting any pressure on the neck if you can -- move her to a harness for example so a collar isn't pulling at the neck; most dogs with SM are generally far more comfortable on a harness. I wouldn't rub at that area or anywhere around the spine if there's any question of a reaction.
There are videos of dogs with SM on
www.smcavalier.com that might be helpful to you. The one of Chester in particular might help put symptoms in some context.
Scratching three times a day (more than once daily, actually), if they are SM scratches, is actually a fair amount of scratching according to the pain assessment diagram used by several of the neurologists to give a pain score to dogs (view it
here). Some neurologists feel scratching is a far less worrying symptom and may just indicate some minor discomfort but others say it does indicate actual damage to an area of the spinal cord and can mean anything from minor discomfort to real pain, so it is good to keep an eye on it. If the diuretic doesn't stop the scratching, most neurologists will then recommend trying gabapentin (neurontin) as the next step.
Did your vet or the neurologist say a lopsided syrinx was abnormal? My understanding is that these are more common that syrinxes right in the center of the spine as more dogs scratch or have symptoms on one side only, but maybe it is the case more that while lopsided syrinxes are less common, they are more commonly associated with pain and symptoms. I do know they tend to be a bit more problematical because they start to press on the side of the spinal cord where they are larger, and this is what starts symptoms, whereas those in the centre take far longer to start pressing on the nerve endings at the top or side of the spinal cord. Dogs then have symptoms primarily on the side where the syrinx is pressing -- eg the dog will scratch to that side or develop areas of pain on that side.
There's a lot of info on my site
www.smcavalier.com and you might be interested in the presentations in the London 2006 area of the research section where there's a presentation on syrinxes and pain. This is in paper five and there are links to the abstract and slides from that presentation.
This is from that paper:
There is a very strong association between maximum syrinx width and pain:
* Asymmetry of syrinx is only found in the dorsal half of the spinal cord, and is associated with pain. 79% of dogs with pain had such a syrinx.
* syrinx length is also associated with pain.
Results – dorsal asymmetry:
* Syrinx asymmetry only found dorsal half spinal cord
* Dogs in pain more likely to have dorsally asymmetrical syrinx
15/19 (79%) - dogs with pain
16/33 (49%) - dogs without pain (p=0.0419)
* Mean length of asymmetrical syrinx
5.15cm - dogs with pain
2.8cm - dogs without pain (p=0.0039)
You can see that in this study, more dogs had assymetrical syrinxes than symmetrical (31 of 52 dogs). These are my notes from that international conference and I am afraid they are not highly detailed but they were checked by the various speakers for accuracy.
Have you let her breeder know about this diagnosis? This is important information for breeders to help their breeding programmes. Also, is this a KC registered dog? If so the scan results would be very valuable to Dr Sarah Blott's work on the condition; I can send you some further information on this privately.