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Shabbat Parashat Vaetchanan 5777

Ask the Rabbi: Animal Experimentation

Rav Daniel Mann

Question: I am working for a medical researcher, and a lot of it includes experimentation on rodents. Let’s just say that these animals’ lives are not always pleasant. Is this permitted, or is it tza’ar baalei chayim (causing pain to animals)? How should I feel about my involvement?


Answer: There is a machloket in the gemara (Bava Metzia 32b) and poskim whether tza’ar baalei chayim is a Torah law or a Rabbinic one, and it is possible that it is a quasi-Torah law (see Encyclopedia HiIchatit Refuit, VI, p. 525). Many mitzvot in the Torah (at least according to some commentators) and Rabbinic laws are based on concern for animals and are to avoid cruelty to them. When and why can this be waived for human purposes?

The simple reading of Tosafot (Avoda Zara 11a) is that tza’ar baalei chayim can be waived only to facilitate an important mitzva. However, the halachic consensus is along the lines of the following Rama (Even Haezer 5:14, based on the Issur V’heter and Terumat Hadeshen): “Anything that is needed for medicine or for other things does not have a prohibition of tza’ar baalei chayim. Therefore, it is permitted to pluck feathers [for quills] from live geese, but the world is careful about that because of cruelty.”

There are at least two approaches to why the prohibition falls in the face of human need. One is that the prohibition is only for being needlessly insensitive. We find regarding bal tachshit (not destroying things) that “destroying” something for a positive reason is permitted because it is, in context, not destructive. Indeed the two mitzvot may be connected as the gemara (Chulin 7b) says – killing an animal for no good reason is ba’al tashchit; keeping it alive but in pain is tza’ar baalei chayim. Thus, if done for a good reason, it is not destructive/cruel.

A second, complimentary approach, is that the Torah teaches us, explicitly and implicitly, that animal rights do not compare to human needs. There are several Torah statements along the line of “Have dominion over the fish … birds …” (Bereishit 1:28). Furthermore, we are permitted to take an animal’s life simply because we desire to eat meat. We may enslave animals to do hard labor, with some restrictions (not Shabbat, muzzled).

There are a few important possible distinctions. Permissibility may depend on the level of pain to which the animal is subjected. Normal agricultural work is not torturous and is permitted. However, the Rama above calls plucking feathers from a live bird cruelty, and says we do not do such things (see Shvut Yaakov III:71). The level of need is also a variable. Some rule that earning extra money is not an excuse (see opinions cited in Minchat Yitzchak VI:145), and while most authorities say that it is a valid reason, it may depend on how painful it will be for the animal (ibid.).

Rav Yaakov Emden (Sheilat Yaavetz I:110) says that tza’ar baalei chayim applies only to animals with which man works (e.g., cattle, horses, donkeys) or perhaps relatively highly cognitive animals (dogs, cats), but not to “lower creatures,” who experience pain differently. According to these opinions, it does not apply to insects, and likely not to rodents.

Looking for cures and treatments for human illnesses is certainly a very valid reason to allow animal experimentation. As several poskim point out, real efforts should be made to ensure the importance of the experimentation, limit the number of animals used, and minimize pain (including using lower species). Suffering animals should be euthanized as promptly as possible. Thankfully many countries have rules to monitor such things, and unfortunately few do a good enough job.

Personally, if you are involved for a short time, it is appropriate to feel somewhat uncomfortable, even if the practice is right (see a scary story about Rabbi Yehuda Hanasi – Bava Metzia 85a). A professional researcher can’t be expected to constantly live with guilt, but it is appropriate to seek ways to heighten sensitivity, emulating Hashem, whose mercy is on all of His creations (see Tehillim 145:9). 

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