When we go camp with our horses we use electric tape for corrals and none of our horses ever bother the fence. I was in my trailer and heard someone yelling for help. She had gave him the shot and he dropped and started thrashing, there was no safe way to control him although one lady tried to hold his head as he has a halter and lead rope on. He started flipping over the fencing and got tangled up in it. He pulled down his corral and 2 more corrals near him. Then he got up with hotwire tape wrapped around him and run off thru the woods. His buddy went with him and two other horses got out and ran to the highway.
The owner and I went to find him and his buddy while others went to get the other horses that had got out. When we found him, like 10 minutes later, he did not have any of the tape left on him, but his back leg was broke.
We were out away from any city, but after many calls to every vet within a 50 mile radius, we finally got a vet out to euthanize him. It was a very tragic event and instilled in me even further to never ever give any horse penicillin. She always pulled back on the syringe to check for blood as did my other friend who was a vet tech when her horse had the same reaction, although her pony survived and was not injured.
There are so many better drugs these days to use that no one should ever take a chance of having this happen. He was a very gentle, kind horse and it was just tragic what happened. Thank goodness the other 2 horses were caught on the highway and we didn't have another horrible incident.