How about calling him:
1. "There goes every last penny I had."
or
2. "I can't take a vacation because someone has to stay home to feed and water this ol' nag."
or
3. "There are only two types of people who own a horse, very wealthy people and very poor people."
or
4. "The two best days of owning a horse are the day you buy it and the day you give it away."
or
5. "Elmer's glue"
I know all these would be good names because my father was a horse trainer and I grew up around horses. If you have a family and you ever want to do something not related to horses, forget it. It ain't happening.
No thanks
but good luck to you