Rabbi Moshe Isserles, Shulchan Aruch, Even Ha'Ezer 5:14
Anything which is necessary in order to effect a cure or for other matters does not entail a violation of the prohibition against tza’ar ba’alei haim… It is therefore permitted to pluck feathers from live geese [while they are alive] and there is no concern on account of tza’ar ba’alei haim. Nevertheless, people refrain from doing so because it constitutes an act of cruelty.

Suggested Discussion Questions:

Is this text suggesting we can or can not make use of animals for our own ends?

What criteria would you add to that in the text about when we can and can not cause animals some pain?

Time Period: Medieval (Geonim through the 16th Century)