A possible complication on the horse situation
SO, horses, we know they basically don't exist in Fallout (yes there's the alleged Avellone email but that's not backed up firmly by actual people, with general statements being more 'implementing them would be technically difficult and raise questions so we didn't).
Except.
Well, in Fallout 3, Broken Steel...terminal entries from the poor bastard running the show repeatedly mention mules.
You know. The sterile offspring of horses and donkeys.
Which would imply the Capital Wasteland has horses and donkeys. Somewhere.
Either that or mules exist and somehow became fertile (or something. Look radiation is weird).
I dunno, I just was wiki-crawling and found these entries and now it's a hilarious complication in one of the oldest lore bits generated pretty much entirely from two lines in a random terminal entry.