yep listerine mouthwash, spray it on with an old well cleaned spray bottle, will clear it up if it is a fungus, works on rain rot also. Thistles look like flat lettuce leaves, they have tiny hair like thorns, and like I said could be poison ivy or oak growing up.
SPray it off with listerine, then let it dry then rub some vaseline like you are doing. If you can't get anything else. If you can get to a tack store look for an anti fungal cream,
Oh it could also be virus related, if so it is contagious, through shared water troughs of feed bukets. If viral the same thing will work and it will clear up on its own.
Last edited by Joe4d; 10-09-2011 at 10:27 PM.