I think this will be the final installment of my series on horse travel, and it’s about the care of the horse on the road.
Horses are among the small number of mammals that cool themselves by sweating. As such, they dehydrate quickly when working hard. At a bare minimum, a horse needs to drink a gallon of water for every hour he is working, just to keep even with fluid loss. Possibly a horse could carry its own water if the journey is short, but generally one will need to rely on way stations or lakes and streams.
A horse that is hot from exercise should not drink cold water. The sudden change in temperature in the stomach can cause circulation problems and/or lead to colic.
A traveling horse also needs a great deal of food. The prescribed ration for Civil War cavalry horses was 14 lbs of hay and 12 lbs of grain daily. Can you imagine hauling all that around if you’re riding cross country? It’s not enough just to let the horse graze all night, although doing so should reduce and possibly even eliminate the hay requirement. In my own books, I tend not to go into details about how these logistics are handled, except to occasionally mention that the horses were put on hobbles to graze overnight, or that the hero or heroine went into town to buy grain.
The same restriction applies to food as to water. A hot horse should be cooled down before being offered hay or grain. If there is any suspicion that the horse is dehydrated (e.g. from travel) and the horse is valued, it’s a good idea to offer some sort of wet mash instead of dry hay or dry grain. Wet foods will help the horse rehydrate.