My latest Fortress has been getting hit by Were-Goats. I thought I'd managed to quarantine all of the injured warriors, but evidently I missed one or two. When the next full moon brought this to my attention, I did a more thorough inspection for injured dwarves, put them all in a squad, and stationed them in the caverns with the intention to wall them out.
Unfortunately, no one ever started construction on the wall, and the squad just moseyed right back into the fortress to get drinks. By the time the next full moon came around, the outbreak had (probably) gotten out of control.
Maybe my next course of action was overkill, but I decided to burrow everyone into the caverns and abandon them to their fate. I figured they'd survive until the next migrant wave. But the dwarves were still being obstinate little shits about constructing walls, so I had to mess around with burrows.
As a result, one dwarf managed to make it back into the fortress just before the wall got built. Luckily he wasn't a were-goat! He's got more food and booze than he could ever hope to consume, so I set him up to alternate between military training and making crafts to stay sane.
Between the were-goat plague, the forgotten beast that showed up, and the gradual but steady flooding after I dug into wet stone just so they'd shut up about not being able to bring water to the injured, nearly everyone in the caverns has died. But migrants have arrived and the fortress will live on!