OMG the exact same injury happened to my horse in Aug. She spent 4 days at the vets. She was on stall rest for a month. It's now Oct and it is still not healed all the way. I had the vet out two weeks ago because it was healing slowly. He said it should have healed completely. His advise was to wait a month and if it does not heal by then he will have to cut the skin around the edges and let the healing process continue. The strange thing is that I was out there with friends petting the horses including her. She wasn't hurt then. My friends left, I went inside the feed room came out and she was standing at her bucket. I notice blood was dripping down her leg. I didn't hear or see it anything, it happened that fast. The bad thing is it was 7 pm on a Friday and I couldn't get hold of a vet and they don't work weekends. All I could do was stop the bleeding, carefully hose it off and wrap it til Monday. When I took her to the vet he sedated her and actually put his finger inside the wound to make sure no wire had broken off inside her leg it was a deep wound. So of course I will be checking your post for updates on your mare's healing progress.