As you know, barbed wire is a big no no with horses. I have a little bit left on our place, and I'm ripping it out every chance I get and replacing it with electro tape.
One thing you could do would be to tighten it up. Loose wire like that is a menace. You can also put a hot wire on the inside on the extended insulators to keep the horses out of it.
Spent a whole hour today laying in a pasture, waiting for a sparkling vampire to show up. Alas, I woke up and looked over, only to find a mound of horse crap. Sigh.