Your poor poor horse. From what you are saying it sounds like the same fencing that we have too
Ours is straight wire, one at the top, middle and bottom.
I can't remember the forum users ID that recently had a horse that went down a cattle grid and sustained dreadful injuries like this, maybe someone will remmber her name for you. She had a dreadfully long nursing period but from what I can remember ended up with excellent results.
Good luck with your baby, I hope she gets better soon.
Hugs
Guisbrogal I think that was debradley and the horse was Honey (?).
I also remember a feature in one of the Equestrian magazines several years ago about a cattle grid incident. The horse pulled through but it was a long haul.