Background: 15 year old TB gelding, eventing Training level. Has had a light schedule since the end of our season in November. A couple of weeks ago, I came down to the barn to find his left front stocked up. Walking/cold hosing/wrapping/bute helped the swelling go down. [IMO this is all unrelated to the issue he has now, but just for a back story.] I noticed when I was picking out his hind feet, he was reluctant to pick up his LH (he has shivers, so this isn’t totally abnormal for him, but his LH is his “better” leg when it comes to shivers), and when he did, he had a hard time flexing his leg upwards. When I was walking him under saddle, he felt short on the LH as well, but it got better the more we walked. He was definitely uneven behind at the trot.
The vet had me put him on daily Equioxx and rest for a week or so. His LF went back to normal (likely related to a scrape he kept re-opening on the front of his fetlock), and he was sound when I rode him last weekend. He was slightly better about picking up his LH, although still “stiff” about it. At that point, I took him off the Equioxx. This past week we’ve had sub-freezing temperatures, so the footing in our ring was frozen, which meant no riding.
Came down yesterday to ride, and I noticed he was having a hard time pivoting on his hind end when I turned him around to to close the gate to his paddock. When I went to pick out his LH, he refused to lift his foot, and when he finally did, it went way up and out to the side, which unbalanced him and made him nearly tip over. (Again, he has shivers, but this degree of reaction is abnormal.)
When he was standing in the crossties, he tends to rest his LH on his toe. On the lunge he’s tracking up fine with his RH, but falling at least two hooves short on the LH. He’s relatively normal at the walk.
Unfortunately for me, I leave tomorrow for a week for Christmas holiday, so the vet won’t be able to see him until I return next week. I spoke with the vet at length and he’s suspecting either his shivers have gotten acutely worse, possibly a hind suspensory, or other injury. (I’m wondering if he injured his stifle or has a pinched sciatic nerve.) In the meantime, he’s back on the Equioxx until I can have the vet look at him.
I’ve known this horse for about 10 years, and his shivers have stayed pretty much the same in terms of acuity. I’m wondering what could possibly be going on here… and hoping to dog it’s not a suspensory!
I know this is a YMMV type of question, but has anyone had this sort of thing happen with their shivers horse? The vet speculates that if it is his shivers getting worse, the muscles have been spasming, which is why the Equioxx helped. However, I’m still wondering if he slipped in the paddock and injured his stifle (although there’s no obvious swelling or heat anywhere along his stifle/leg) or SI.
).
So now I just keep on runing through worst case scenarios in my mind: pelvic fracture, hind suspensory, something broken, etc. 
