Hmm, I'd definitely be looking for a second opinion I'm afraid, telling you it was "mild" based on the syrinx sounds as though they are very misinformed regarding CM/SM.
We have two Cav's, Misty with CM and SM, with three syrinxes, and Murphy with "just" CM, who is pre-syrix. With Misty it was easy for us to suspect CM/SM as she scratched a lot, especially when getting excited about going for walks, and she rubbed her head along the floor and furniture a lot too. Her Neuro was shocked at how active she is considering the size and width of the syrinx at her neck. Murphy on the other hand showed very little scratching, but in June last year he started having what we call panic attacks, we had our vet stumped by what was causing them, as they would happen so infequently, and without warning. They would reduce Murphy into a panting, drool soaked mess, who literally tried to climb inside of you to get some comfort. Our vet sent us to a Neuro just in case, and it turned out he has CM, and some degenerative disks in his neck.
Both are now on 100mg of Gabapentin x 3, Cemetidine x3, and Misty is also on Tramadol x 3 and 2.5mg of Pred 1. We also saw a pain specialist for Murphy, and she gave us some good advice about their exercise. She said that Cavaliers have so much serotonin that when they are excited, e.g going out for a walk, they "forget" how much pain they are in and act like nothing is wrong, and exert themselves way beyond the point they should. I've seen it many times with my two, they are mopping about the house sick, but the minute you lift the leads, they are up and tails wagging. I even saw this with Misty after I came home to find 20 plus piles of sick and bile in the house, after she'd eaten something she shouldn't. She rushed up to greet me, but then started staggering sideways as she was so dehydrated! And no matter how bad a day she is having if there are a lot of changes in air pressure, she'd still chase her tennis ball across the field until she dropped. But the point the pain specialist made was we need to make these decisions for them. If they are ill, we need to say "no" you can't do that, or they'll just go ahead and do it due to their excitement.
I'm not having a go at you, please believe me, but I worry that all this running and jumping about could be detrimental to his recovery from surgery, especially seeing how much pain he appears to be in. Any dog that's crying at anytime is in a lot of pain.
Paula - mum to Murphy(6) & Misty(7), and Jerry our cat.