Animals have been bred for medicine for at least a few hundred years. Leeches were used in Mideval France as blood clots. In America, some leech farmers (Eeewwwww!!!!) could boast that they made ~$1,000,000 a year. This is a lot for even today, but it was worth a lot more back then. Also, sadly but truly, many animals, most commonly rats and mice, are used to test drugs in labs.