I think this happened in the 1990's and I believe it's true.
This happened on a ship in transit from California to Hawaii. A bull was carried in a specially modified container (this is not unusual). Somehow, in the middle of the night, the bull got out. An entrance to the engine room was open and there was a set of stairs that the bull must have taken for a cattle chute. The bull slid down the chute and ended up on the main platform. The watch Engineer came out of the control room on a routine round and came upon the bull right in front of the main switchboard. They both freaked out and the bull kicked the switchboard causing the generator to go off line and the lights to go out. Everything on the ship shut down. In the middle of the ocean. In the middle of the night. The emergency lighting came on and eventually everybody came down to the engine room. The bull was corralled and coaxed back up the chute. The boilers and turbines were started again and everybody had a great sea story.