Earlier this month, Rick attended an advanced neck and back ISELP seminar. What he learned there prompted him to take a look at Lance's neck. So tonight he watched Lance move on the lead-line, lunge line, and under saddle, then he ultrasounded both sides of his neck. Diagnosis: synovitis encapsulitis – arthritis, basically. This is probably what has caused Lance's stumbles and falls; he's not just lazy!
Rick plans to x-ray Lance's neck as well, just to get as much information as possible, then inject the problem areas (C6/7 on both sides, C5 and C7/T1 on the right) with steroid. Depending on the results, Rick may follow that up with IRAP therapy. (Yes, I am very thankful to be married to an equine vet!)
I went through this with Russell; Rick gave him repeated neck injections with diminishing returns so we ended up retiring him. Maybe it will work better for my Lancelot; we'll see.