Induce labor in a mare? Take a nap.
Cure equine constipation? Load them in a clean trailer.
Cure equine insomnia? Enter them in a halter class.
Get a horse to stay very calm and laid back? Enter them in a liberty class.
Get a horse to wash their own feet? Clean the water trough and fill it with fresh water.
Get a mare to come in heat? Take her to a show.
Get a mare in foal the first cover? Let the wrong stallion get out of his stall.
Make sure that a mare has that beautiful, perfectly marked foal you always wanted? Sell her before she foals.
Get a show horse to set up perfect and really stretch? Get him out late at night or anytime no one is a round to see him.
Induce a cold snap in the weather? Clip a horse.
Make it rain? Mow a field of hay.
Make a small fortune in the horse business? Start with a large one.
This is one of those things that has been shared around the internet a lot without attribution. If anyone knows who wrote this, please let me know, I’d love to give credit.