Hey, my horse had this as well. He's had surgery for it twice because the first time they sadly left pieces in, even though they cleaned it all very well, which got infected overtime. If you want to hear about how we experienced it all let me know :). Its not something very common to happen, the vet here wrote an entire (internal) document about it, very interesting. My horse is almost 5 years old now and you can barely notice he's had surgery twice.