There are borderline cases in which a person has a genuine need but meeting that need will cause an animal to suffer. The question is whether the human benefit is significant enough to justify the suffering. The guiding principle is that when the suffering is caused for human benefit and not out of cruelty, there is no prohibition. Nevertheless, since the need is not absolute, one should ideally avoid causing the suffering when possible. The more the animal suffers, and the less necessary the act is for the person, the more proper it is to refrain. Ordinary human judgment and accepted practice are used to assess both sides: how substantial the human need is, and how severe the animal’s suffering is. On that basis, one can determine when it is proper to refrain and when the act should even be prohibited.
For example, strictly speaking, one may pluck feathers from living geese to make quills. But since this causes the geese great suffering, and feathers can instead be taken from geese after slaughter, it is proper to avoid doing so (Terumat ha-Deshen; Rema EH 5:14).
Similarly, one should avoid plucking feathers from a bird’s neck merely to clear the place of slaughter, since this causes needless suffering. If, however, the slaughterer is not skilled enough to slaughter properly without doing so, it is permitted (Or Zaru’a; Rema YD 24:8).
Likewise, one may crop a dog’s ears or dock its tail so that it will look more attractive, since this is done for the owner’s benefit, not out of cruelty. Nevertheless, out of compassion, it is better not to cause the dog suffering. A similar principle applies to a parrot: strictly speaking, one may cut a small part of its tongue so that it can produce words, since this gives its owners pleasure. Ideally, however, it is better to have compassion on the parrot and refrain. If avoiding the procedure would lead the owner not to keep the dog or parrot at all, then the procedure is considered a genuine need for that owner. He may therefore arrange for it to be done, just as people are willing to spend money and undergo surgery to improve their appearance.
One may train animals even when this requires striking them lightly. Even if the training requires harsher strikes, it is permitted, though avoiding such methods is an act of piety. If the animal would otherwise not be used and would likely be killed, even this more difficult form of training is permitted as ordinary practice.
Strictly speaking, one may hunt animals in order to use their hides for coats, wallets, and similar items. As an act of piety, however, it is proper to be stringent. In the past, many were not stringent about this, because people relied on animal hides for warm coats and blankets. Today, when coats and blankets can be made from synthetic materials, it is proper, as an act of piety, not to hunt animals solely for their hides (see Mayim Ḥayim 2:50, by R. Ḥayim David HaLevi).
