7 year cryptorchid gelded 4 months ago

Question
Hi.  I am an experienced rider (started riding at 5 and competed very actively in jumping for over 15 years in Latin America).  After being away from the sport for several years I was offered the opportunity to train a 7 year old cryptorchid stallion (TB/Percheron). I am in good physical condition and still consider myself an advanced rider. This horse has lived with a very old mare (pony) most of his life and treats her with respect.  I started working with him (at that barn where he lived with the older mare) but he is somewhat aggressive, distracted and in general difficult so I requested that he have the surgery to be gelded also thinking about the future when he would have to interact with other horses.  The surgery took place 4.5 months ago and was successful. The horse's owner had to move him to a new barn where there are 5 more horses (3 mares and two geldings). I don't own the horse but I can tell (from prior experience training horses) that he has a lot of potential.  He works very well when the other horses at the barn are in their stalls even if he can see them.  But even now (4+ months after the successful surgery) he still displays some (not much) stallion-like behavior and also completely loses his focus when some of the other horses are around (especially one of the mares and one of the geldings - the gelding in particular seems to stress him out).  I really enjoy working with this horse and he is very easygoing and trainable (when not distracted). My question is: I am not sure how to socialize him and how to make sure he can maximize his potential and not be overwhelmed and distracted when the other horses are around.  (He can be very relaxed when I'm working with or riding him, but when he sees the other horses he immediately becomes very tense, arches his neck and only wants to look in that direction.  I am very firm in trying to regain his attention but it turns into a situation where even though he doesn't rear or buck, nothing significant can be accomplished since he's too distracted).  
Please let me know any ideas or suggestions on how to socialize this horse (I don't think giving up should be an option).
Thanks!

Answer
Hi Dan!  

    Great question!  And with that in mind, I offer three thoughts.  One, congratulations, you are absolutely correct that giving up is NOT an option.  Two, are you able to confirm that both testicles were completely removed?  And finally, in older stallions, such as seven and above, four months is a subjective time frame for gelding like compliance.
    Was the talented horse in question ever bred?  If so, it is going to take a great deal longer for that testosterone to process and exit his system.  If not, that's ok too!  A lot of times, with stallions, their reaction to the stimulus around them is a learned habit and maybe not so much fueled by an instinct that should be gone.  Four months is a very short time for a horse to forget they are no longer a squealing, presenting stallion, especially when they have done it for seven years!  
    It sounds like you are on the right track and just to help you out a little more, you might be in for a stallion-like summer, simply because he is adjusting to relearning about himself (which its not uncommon for this to take 4-6 months in older horses).  But, this can absolutely be dealt with!
    I recommend a lot of trail riding with others.  Trail riding forces him to think about what he is doing and while he is doing that, practice moving him to the front, to the back, to the middle and require that he behave himself in the process.  It sounds like you are riding a very level headed horse who just follows his instincts, so just continue to respect the "stallion" boundaries you have always acknowledged, at least until he shows you that he is winding down.  In the arena, keep his mind engaged.  If he is comfortable enough in his work that he can take his mind off of you for a second, its time to up the anty.  Assign him a new and challenging task, do whatever you must to get his attention, but demand that he be listening to YOU!
    As for the aggression, you can fully anticipate that to linger around as well for a while.  I too just gelded a stallion for his aggression and I too am still dealing with it.  Unsolicited aggression towards humans and other horses is a stallions way of asserting dominance.  Dominance over geldings, making sure they have no questions as to who the mare belongs to, and dominance over the human that they are in charge and will do as they please.  Left to their own devices, stallions are a tough animal to rein in, so be sure that you are constantly reasserting your dominance, by requiring his attention be on you, by being fearless in your confrontations with him and making sure that he follows through on YOUR requests.  Treat him as you would an unruly dangerous child and take care of yourself and you will be of the greatest assistance to him as he relearns who he is.
    All in all, give him a job and demand excellence through communication and teamwork.  Let me know if there is anything else I can do to help you and once again, thanks for your question!