What Wynette says. DON'T WAIT. Just call. Really. If the horse *is* in trouble, be aware they can go downhill pretty fast, or sustain sufficient damage to their systems that it can be quite hard to nurse them back to health. If you're concerned about anonymity (w/r/t your neighbor), say so when you call, it is a really really common thing, the person you're talking to isn't going to think you're weird or anything, truly.
JMO,
Pat
JMO,
Pat