studdy gelding mustang

Question
Hi
We have an 11 year old adopted mustang gelding.(Ihope!!!) He has gotten along with our herd of 3 other geldings and 1 mare.  He herded the mare around quite a bit when he first arrived but then settled down.
I bought another mare and introduced her slowly to our herd.  She was out with our mustang and another gelding, (lowest of the herd), when she came into heat.  They were both checking her out and very interested.  By morning, the mustang was mounting her.  Now he has become extemely aggressive towards our other gelding (an arab pony who thinks he is top of the herd!)  The mustang has pinned the pony and is biting and kicking him.  This is happening even when the mare is not out with them.(she has been separated from the mustang)
I would like to keep the whole herd together.  Is this something that just may take time to settle or is there a way to break the mustang of his studdy behavior?
Thank you!!


Answer
Hi Kate,
         There are some geldings who retain studdy behavior even when they have been castrated. I own a 15 year old Mustang gelding who tries to mount my mare, whenever he get s a chance. At your geldings age, there is really no way to change that behavior as it is ingrained. Much could depend of how old he was when he was gelded. I would have the Vet pull some blood to check his hormone levels to make sure that he was gelded correctly and did not retain a testicle. If your pasture is big enough for the horses to get away from each other then you should be able to put them together. Gven some time, they will work out the pecking order. You might also want to take your new gelding out of the pasture and introduce him to the others over the fence. This way they can get to know each other better.  

Lisa