Just off the top of my head without looking up the facts. I remember there were federal regulations about care of livestock. Cattle were required to be "rested" every so many hours- 20 hours? I don't remember the exact amount of time. They had to be let out of cars to be fed, watered, etc. However, hogs could be watered inside the cars by spraying water through the sides. Sounds like a hog drencher would be the apparatus that would allow that.
I remember hearing from a railroader about a crew that decided to cut the procedure even closer. There was a water tower for steam locomotives with water from a cold mountain-fed stream. The crew decided to water the hogs by removing the spout from the water tower and running the cars past the running water. The extremely cold water shocked the hogs and killed them, resulting in a big fine for the railroad, damage claims from shippers, sanctions against the crew etc.