Worried about my older guy (18) years

[Sharon Leboffe]

Yesterday I took Canseco out for a warm up ride. We walked for about 30 minutes, then did short transitions from gaiting about 100 yds, walking, cantering about 100 yds, walking. When we came in and gaited around the arena, he dropped his front legs (felt like they just turned to jelly for a second) then he scrambled and we walked to the cross ties. He doesn't seem lame, no swelling, no heat. Just like nothing happened. But it did, and I'm concerned. What could have caused him to drop like that? I know he is getting on in years and he is on supplements. I always warm him up before a ride and he has always moved out with no problems. Has anyone else experienced anything like this? Thanks. Sharon L. Sorry, didn't mean to post on "Training and Tack."

[Monty]

Trying to think of reasons he may have stumbled - Monty does it if his hooves are even a tad long -
What was the ground when he stumbled ? Gravel ? May have hit a big sharp stone - we were told by a vet not to trim any off his heel ,after he had a stone bruise. He has thin soles. Showed in ex-rays.
Monty is 22 and seemed to be having some stiffness occasionally - plus he was grumpy on those days - I put him on MSN and he is back to his old, Mr Mellow ,self . It does take a while for you to notice a difference.At least a month. Wouldn't hurt to try it .