Our Gemara on Amud Aleph discusses an interesting moral and halachic dilemma regarding the Biblical directive to allow the animal to eat while it is working on the threshing floor:

בְּעוֹ מִינֵּיהּ מֵרַב שֵׁשֶׁת: הָיְתָה אוֹכֶלֶת וּמַתְרֶזֶת, מַהוּ? מִשּׁוּם דִּמְעַלֵּי לַהּ הוּא, וְהָא לָא מְעַלֵּי לַהּ? אוֹ דִלְמָא דְּחָזְיָא וּמִצְטַעֲרָא, וְהָא חָזְיָא וּמִצְטַעֲרָא?

If the animal was eating from the produce it was threshing, and it was excreting diarrhea [matrezet], what is the halakha? The Gemara explains the sides of the dilemma: Is the reason that one must let the animal eat because the food is good for it, and this produce is evidently not good for it, and therefore the animal should be muzzled to prevent it from harm? Or perhaps the reason for the prohibition against muzzling is that it sees food and suffers when it cannot eat, and this one also sees food and suffers when it cannot eat.

Rav Soloveitchik (Reshimas Shiurim) explains that the question revolves around what is the priority of the commandment? Is it to be sensitive to the animal’s immediate suffering in seeing the food and not eating, or to its long term health and suffering. If the animal was indulged now, it would suffer later from painful bout of diarrhea.

It is notable that with humans we have no such problem. Does anyone think it is a kindness to allow a child to eat sweets until he is sick, or for that matter, to give an adult a cigarette? Generally speaking, with humans the ultimate benevolent intention guides the mitzvah. This is why l’shon hora is permitted when there is a constructive motive and outcome. Swine doesn’t become kosher from good intentions, but chessed depends on intention and whether there are ultimately good results. This is probably what the Gemara (Berachos 33a) means when it  says, “It is forbidden to have mercy on a person who shows no intelligence (judgment or self-management).” However, this is in regard to a human being, who has transcendent and long term goals. On the other hand, since an animal has a less complex destiny and purpose in life, our Gemara’s question is that perhaps we should only consider its immediate gratification. Or, even so, should we care about its long term suffering?