good horse gone crazy

Question
Hi...thanks for looking at this...we have a 15yr. old Tenn.. Walker...approx 15 hands...had him for 5yrs...he is a gelding that never caused any real problems in the past..actually very lazy...he likes to turn on you when mounting..that is not the big issue..this year he gets real excited when we meet other horses on the trail..starts prancing..getting VERY excited ..backing you into things ...rearing up..turning..hard to control..circling him only makes him more nuts...the rest of the ride he acts like he wants to bust loose..... He is out 24/7...year round...he was living in a pasture with 7 other horses ..all geldings...3 of which have been there about a year...and are a true gang bullying the other horses.. this horse is about in the middle of the pecking order...he eats grass ,with occasional graining... We have made some changes..no grain..put him in with the mares..stepped up the ground work... his saddle fits...you can rub him all over ..no sore spots... At this time it is hard to feel comfortable with him on the trail...his excitement level turn into a 10 when he meets other horses on the trail..a follower..wants to turn into a leader when excited...not wanting other horses in the lead..and will do anything to prove this point when excited...including getting you off his back...last year you could pass other horses all day long with much concern...why does he get soooo excited at these times and become hard to control... your help is appreciated..  

Answer
First thing I would do if you have not is get him a vet check. Make sure the vet checks his vision and hearing which if  faulty could be causing him to act this way. If the vet check comes back with no issues I would start to train him like you would a green horse you were going to ride on the trails. First bring him out with one or two horses and make sure that you hold him back so that at first he is at the back of the pack. Since you said circling does not work then I would dismount whenever he acts up and longe him for 10-15 minutes so that he knows that he is not able to get away with this behavior. When he does well with the few horses you can then add more and see how he does. But it does sound as though it could be a vision issue.

Lisa