Looks like she simply misjudged her jump and her back legs went in between the 2nd and 3rd wires. Too bad for sure.

I found a 13 point buck once with electric fence wire wrapped around his antlers and under his throat, the wire under his throat had tightened so much that it appears he suffocated. He had the wire on sometime too as one side was free of velvet and the otherside was dried crusty velvet that he couldnt rub.

Your case is different but in that case it could have been prevented had someone just taken the time to big up their garbage.