I've had my share of this happening for a variety of reasons. But I have the habit now of checking the perimeter fence line each morning, looking for weak points, for breaks. I double check the gates when I go through. But still.... It's not uncommon for a feral pig to come by and damage a fence. Or for a branch to fall in it. As long as the livestock stays on my own 20 acres, I don't consider it a disaster. But they surely can cause havoc within my 20 acres.
Just last month the sheep broke out of the back pasture. The wire gate gave way, a victim of the acid rain. I hadn't noticed the bottom restraining wire getting weak, but those sheep guys did. It was closer to their eye level and they spotted it. I'm guessing that one of them was rubbing themselves in the gate post, relieving an annoying itch, when the bottom of the gate gave way. It was a glorious opportunity to confirm that the grass is greener on the other side of the fence!
Mostly the flock ate the grass. They entered an area where they've been allow to graze before, but I normally erect protective barriers around things I don't want them to eat. A simple hotwire can protect bee hives, gardens, or fruit trees. Since they understand and respect a hotwire, I don't even need to have it hooked up to a fence charger for it to keep the sheep at bay. But alas, no barrier hotwires. Results........
Lilikoi vines defoliated within reach. Several small vines got chewed through, thus killed.
Young citrus tree defoliated and pruned. Luckily it's starting to push new leaves.
Happily I discovered the breakout before things got worse. But in the past I've had the entire veggie garden eaten! Yikes.
The latest breakout was a couple days ago. Calico, the goat, learned how to work the gate latch. Smart goat. Of course, every other goat followed her to freedom. No damage done, but the gate now sports a chain and clip to help keep it shut from inquisitive goat lips.
The real danger comes when livestock leave the farm. If they get onto a roadway, they could cause an accident. Bad news. Thus I am very diligent about maintaining my perimeter fence.