My horse is off the track and when she's really stressed and I'm not standing close by, she starts to weave. She's not one of those anxious high strung thoroughbreds but she is very very sensitive. Things like high winds or a storm front coming in or another horse getting loose and running around the farm or the pigs screaming when the vet vaccinates them will cause her to weave ever so slightly in cross ties. If she's in her stall, I thinkshe feels safe and typically doesn't weave. I also give her massages often because she does have back problems since she's so long backed. I probably should have her adjusted by the chiropractor too, but at $160 for 20 minutes...it's a bit hard on the wallet. A pinched nerve sounds like a good possiblity in the other horse's case. I'd hate to think how hard a wrench that trainer did to that poor horse to cause such a result.