Basic (hopefully short-ish) explanation: 5yo TB gelding, 16hh square conformation, short back, kind of straight hind legs. Off track 1 year, been in semi-serious work for about 3 months. Finished racing due to bleeding. Has started jumping (trot poles and cavaletti only), jumping no higher than 60cms as I don't want to overface him. When he first came off the track he was very stiff in hind and front, reluctant to stretch out, short, choppy strides. Barefoot the last 8 months, unbelievable difference. HOWEVER still very tight thru hind end, getting regular massaging and stretching. On Sat morning worked him over a few jumps, up to 70cms, but not much more work than normal, although he was very tired afterwards and rested for the rest of the day. Sunday led him out in hand for 1 1/2 hours for graze and walk. Monday morning went to ride him (intending on doing a bit of long & low, trotting in large circles etc) and left his rug on while picking out his feet (really cold at 6am in Oz at this time of year!) and as I picked out his hind feet he kind of tripped and stumbled, I tore the rug off straight away & he was displaying the same symptoms as I've read about with the locking stifle, however his whole muscle was twitching and all the muscles on his hind end, esp. Hand strings were rock hard and he couldn't move without dragging this particular leg (near hind) I tried to turn him to "unlock" it, but to no avail, so I unclipped him to see what he would do...he walked off like on the side kind of thing, really favouring the affected leg. I massaged the area and encouraged him to walk it out (you could tell by his face he was in a lot of pain) and after about 5 minutes he was happier and walking almost normally, BUT his muscles are still tighter than usual, and extremely well defined, on both sides. My friend checked him periodically during the day while I was at work & he was alternatively resting each hind leg, but not acting any different to normal. In the arvo I walked him out in hand, then massaged hind end for about 1/2 hour.
I'm really sorry this is so long, thanks to those of you that stuck through it for reading!
Is this locking patella or could it be muscle spasm due to work load 2 days before? The vet will come during the week, I'd like to get a blood test to check for Vit. E & selenium (he's already on Vit. E but perhaps not enough). His diet is 2 biscuits of lucurne hay, half a bucket of oaten chaff, 1 small scoop of pellets and 1/2 scoop soaked oats. I'm in the middle of transitioning him off the bagged chaff & pellets as he is still sensitive over stones & I'm starting to try the suggested barefoot diet.
Thanks heaps in advance