Pit
Pits are hazardous to your health. They can be deadly, especially for little dogs and kittens. They can be filled with boulders.
"The dwarf falls into a pit!"
There is an extended command, "#untrap", that lets you reach for the dwarf and try to rescue it from the pit.
"You reach for the dwarf. The dwarf is grateful!"
Congratulations! You now have a peaceful dwarf.
Actually, you probably want to leave monsters in the pit, but you can use "#untrap" to rescue your own pets from pits. If the pet "backs away skeptically", try repeating "#untrap" several times.