Subscribe to the Daily Daf Yomi Summary here.
The Gemora (Bava Kamma 115b) says that it is forbidden to drink from water that has been left uncovered for there is a concern that a poisonous snake drank from it and left its venom inside. Te Gemora rules that one cannot give this water to an animal.
Rashi explains that the rationale is that we are concerned that one may slaughter the animal and it will be dangerous to the person who eats from this animal.
Tosfos points out that Rashi’s approach would only apply to a kosher animal, but in truth this halachah should apply to a non-kosher animal as well, because there is a violation of ba’al tashchis - the killing of an animal for no reason at all.
Tosfos proves this from a Gemora in Avoda Zara 30b that it is only permitted to feed it to a cat (snake eater) which will not be damaged by the venom. This implies that it would be forbidden to feed it to other non-kosher animals that will be poisoned by the venom.
Reb Avi Lebowitz points out something interesting from Tosfos regarding ba’al tashchis. Usually we refer to something as wasteful because it has a function to serve a human and it is being wasted. But in a case where the object provides no direct benefit to a human being, one can argue that it is permitted to waste it without any violation of ba’al tashchis. Tosfos says that this is not true, because even a non-kosher animal, similar to a cat that is not designated to assist people in carrying loads or plowing a field, nevertheless, it cannot be killed for any reason and would constitute a violation of ba’al tashchis.
It is noteworthy that the Halachah L’Moshe writes that according to Tosfos, who maintains that the prohibition against giving these animals to drink from the uncovered water is because of ba’al tashchis, this would apply only to one’s own animal and an animal belonging to his fellow. However, it would be permitted to give this water to an ownerless animal, for this prohibition is not applicable to animals which are hefker.