Speed Racer has the right idea. I'd also tell my friend NOT to move the mare until she is confirmed in foal or given the shot. They'll try to pass it off as having happened somewhere else, by someone else, etc.
I'd also explain to the friend (using the net and proof) how much time, money, and effort go into the cute little foal. People would be suprised if they kept track of every dime spent on preggers and babies.
"Light travels faster than sound. That's why some people appear bright until you hear them speak."
Larry the Cable Guy