Is it possible for them to heal on their own? One of my large 5 month old large black guilts developed a hernia about two months ago. The sac was about the size of a tennis ball and the hole in the abdomen was just big enough to put a finger in. The sac has been shrinking over the past two weeks, and is practically gone now. I haven't felt to see if the hole has closed, but I will this evening. I just wonder if its possible. I hope so, and certainly looks so. I guess if the hole is getting smaller too then I will have my answer! Silly me.