Study Finds Link Between Chronic Pain and Aggression in Horses – 4/13/11

French researchers who examined riding horses using five standardized behavioral tests have found that at least 75% of those with vertebral problems demonstrated aggressive behavior toward humans. The findings could help “alter the perception humans have of ‘bad tempered’ animals. Chronic pain should not be overlooked as a cause of aggression in horses,” the lead researcher said.
CLICK HERE to see the link at TheHorse.com

I’ve noted this in only a couple of horses over the years.  If your horse’s behavior has changed recently, and unexpectedly, it might be worth a thorough physical exam.  Chronic pain is, well, a pain.