About 2wks ago, my 23yr old gelding (Hotshot) started acting different.. we have had him about 20 yrs, and he has always been the calmest, laziest horse ever. handicapped and disabled kids used to ride him all over the place...He always had a nice slow-paced walk..hardly anything spooked him.. Now, all the sudden he is acting completely different.. he is spooking at the slightest things when i ride him.. things that he's been around his whole life spook him now...plastic bags,dogs, cars, etc. he has rode the same trails for over 20yrs, now all the sudden he's scared? nothing bad has happened to him while we were riding.. we thought it might be his eyes or something, so we got the vet to come out.. his eyes are fine, but he does have mild asthma and COPD. other than that hes healthy... i have never had a horse as old as him, so i dont know.. could it be his age or something?