Like most prey animals, a rabbit's first instinct when frightened is to escape the perceived danger. Among their own kind, however, they can be extremely and even viciously territorial, causing a startling amount of damage in the blink of an eye.
My junior buck, Mousse, learned that hard lesson over the weekend.
The bucks are housed next to one another, with 1-2" gaps between the cages to prevent injuries from territorial disputes, but smaller noses can reach through further, and Mousse's neighbor obligingly tried to remove a rather large chunk of his lip.
I brought Mousse in the house, cleaned him up a little (he'd already groomed himself, so there was just the open wound and a significant amount of swelling from the trauma itself), lined up the tissue as much as the swelling would allow, then applied some super glue to try and hold it in place during the healing process.
I put him back out in a cage after the glue had set, with freshly washed bowls for food and water, and gave him a large helping of hay as well. His cage is now on the upper deck of the cage rack, so he has NO neighbors that can bother or injure him while he recuperates.
Unfortunately by morning, though Mousse seemed fine otherwise, the glue didn't hold, so he's got a section of lip that's dangling, and may or may not be able to heal up without causing further issues.