Keep it clean firstly. A nice scrubbing with some Betadine or other wound wash would be good.....personally, i wouldn't wrap it or anything...but others with more experience in wounds might know better than I.
Wound cleansing and some SWAT ointment to keep flies from getting in there and causing problems....would be what I would do...oh, and keeping her out of the mud.
hopefully her pasture isn't too muddy, though mud is everywhere this time of year.
It doesn't look bad to me.....not sure I'd call the vet in unless there is oozing of the wound, swelling, heat or increased pain.....for now, it looks like something that, if kept clean and fly free, should heal up quickly.