So my horse (12 YO TB Gelding) has a best friend (5 YO QH/Trak Gelding). My horse won't get in the trailer without his best friend, is depressed if he can't get turned out with his best friend, etc. And the feeling is mutual- his best friend freaks out when my horse isn't around. They're endearingly, yet annoyingly, connected at the hip/head/heart.

So last summer, my horse was seen mounting his best friend while turned out one afternoon. That was the first time any of us had seen it happen. But my horse did it again last night- mounted his best friend. Of course, this could be happening all the time when they're turned out together and nobody is around, but regardless, I'm baffled by the behavior.

I have a female dog who mounts our male cats, and the vet has told us that it's a dominance behavior. My horse doesn't display any other 'studdy' type tendencies other than mounting his BFF, so could this be a dominance issue? Should I have his hormones checked?

The only other 'off' behavior I've seen out of my horse is that he is constantly putting his face in his BBF's groin region. For a while I thought that perhaps it was an 'identification' behavior, like dogs who sniff each other's rear ends; but I'm no equine behaviorist so I have no idea what he's doing under there.

I don't want him to hurt the other horse's back with all the climbing on top of him; and let's be honest- his hock injections are only going to last so long with this kind of nonsense.

Any input or thoughts would be appreciated. I'm not quite sure what to do about this. Thanks in advance!