What can I do for my horses injured leg?

When my horse was tethered out in this open area of gr at my house she got her back left leg caught in the tether line that she was tied to and in the soft area right above her hoof is cut and I need to know what to put on it to relive th pain and to keep it form getting infected. We put some scarlet oil on it but she didn't like it I think it stung. Does scarlet oil help it or not? Please help me Today she is a bit lame on the foot she hurt!