Let someone else pick your horses back feet the first few days lol. My horse swished her tail and nearly yanked mine out 2 days after i got it (double) pierced . That hurt like HELL, let me just say! I just make sure I clean new piercings really well after I come home from the barn. I've never had any get infected and I have 8 ear piercings and my nose pierced.
"I think animal testing is a terrible idea, they get all nervous and give silly answers."
-fry & laurie
I left mine alone. I noticed that once I started cleaning my tragus piercing regularly that it actually got more tender and it got infected. So... I learned my lesson and instead of cleaning it every day, I just ran it under the water while I was in the shower. And poof, the infection and tenderness magically disappeared!
Other than that you could always use a small piece of tape or a bandaid to cover it while at the barn if you're concerned about that.
Also, I was told to use Witch Hazel on my piercing every once in a while. I just poured a little bit of it on my piercing and let it air dry. That seemed to help also.