Dear Rabbi Slifkin,
Today’s daf discusses the case from the Mishnah (42a) that states that animals become Tereifos by being attacked and clawed ("Derisah") by various types of wild animals and birds. RASHI (42a, DH Derusas ha'Ze'ev) writes that the reason why "Derisah" renders an animal a Tereifah is that the attacker "hits with its claws, and injects poison [into its victim] and burns it." Similarly, Rashi 52b (DH Aval b'Makom) states that the attacking animal "gets angry, and it has a strong poison which it injects into it (its victim) when it hits it with its claws." This explanation is difficult for me, because as far as I am aware, none of the predatory animals and birds listed in the Mishnah have any poison that they inject through their claws into their prey. Is there any other explanation you are aware of?
In response, here is an extract from the chapter on wolves in my forthcoming Torah Encyclopedia of the Animal Kingdom:
An animal is only kosher for consumption if it is in good physical health at the time of slaughter. The Mishnah lists various terefos, fatal defects, which render an animal prohibited for use as food. One of these fatal defects is a mauling by a wolf:
These are the terefos in domesticated animals… if it fell from a roof, if most of its ribs were broken, a mauling by a wolf; Rabbi Yehudah says, a mauling by a wolf [is considered a fatal defect] with a small domestic animal, and a mauling by a lion [is considered a fatal defect] with a large animal. (Mishnah, Chullin 3:1)Although wolves usually hunt in packs, single wolves are capable of bringing down even very large prey such as moose or bison. They usually prefer not to take on such prey, however, since one kick from a moose can disembowel the wolf. Furthermore, the wolves of North America, which bring down such large prey, are much bigger animals than the wolves of Israel and the surrounding region. While North American wolves average 100 pounds, with the record specimen weighing 175 pounds, the wolves of the Middle East average only about 50 pounds and take much smaller prey. Thus, from a halachic standpoint, if a wolf mounts an unsuccessful attack against a large animal such as a cow, the animal is not considered to be mortally wounded and it may still be slaughtered for human consumption. Only with small livestock, such as sheep and goats, is a mauling by a wolf considered a fatal defect. The Talmud further clarifies that a wolf is the smallest creature with which a mauling on a small domestic animal renders it as possessing a fatal defect.
Unfortunately, these laws give rise to difficult contradictions with our knowledge of wolves. One difficulty is that the Talmud states that the result of such maulings is that venom is injected into the prey animal (Chullin 53a). Needless to say, this is not consistent with modern zoological knowledge of wolves.
One solution presented for such difficulties (see Michtav Me-Eliyahu, vol. IV, p. 355, footnote 4) is that the Talmud is not referring to a chemical venom generated by the animal, but rather to infections caused by bacteria accumulating in the animal. Such "venom" certainly exists:
“Many people mauled by lions have died from wounds that should have been survivable: the meat caked under the attackers’ claws and teeth injected the victims with disease, and they died in a gangrenous fever.” Gordon Grice, The Red Hourglass: Lives of the Predators (London: Penguin Books 1998), p. 104.
This answer is offered with regard to why the cat is listed as a creature whose mauling is considered a fatal defect, whereas a dog is not (see Chullin 53a). It is explained that since cats have long retractable claws, dirt can accumulate beneath them. However this explanation falls short with our discussion, since the wolf is listed as an animal that can cause such damage, even though it is physiologically essentially the same as a dog rather than a cat.
A second difficulty is that the Talmud rules that these maulings which are rated as causing fatal defects are referring to maulings inflicted with the claws, not with the teeth. This, too, conflicts with contemporary observations of wolves, which reveal that wolves never attack prey with their claws, only with their teeth. The reason for this reflects the very different hunting strategy of wolves compared to members of the cat family such as lions and leopards. A big cat is an ambush predator. It is not built for running at speed, but rather for firmly seizing its prey. It uses its strong arms and claws to grasp its prey, enabling it to make a killing bite in a precise spot. Wolves, on the other hand, are pursuit predators. The legs of a wolf are slender, and the paws not jointed for grasping; its body is built for long-distance pursuit, not for bringing down prey. The wolf’s claws are strong, but very blunt, because the tips are worn off by constant contact with the ground. These are used for digging and gripping the earth while running, not for seizing or killing prey. Wolves kill with a large number of minor slashing bites, rather than the single lethal bite of a big cat.
These contradictions resist simple resolutions that preserve the correctness of both the Talmud and modern zoology. It appears that they force one to take sides in the centuries-old dispute concerning statements in the Talmud that are contradicted by science.