According to the Mishnah, if an animal ate hardufni – nerium oleander – it remains kosher. If the animal was bitten by a snake or if it drank poison, the Mishnah rules it does not become a terefah, yet it is forbidden to eat for reasons of danger.Shmuel teaches, however, that some poisons will render the animal a terefah. An animal that eats hiltit – Ferula assafoetida – for example, would become a terefah. He explains that hiltit is such a powerful substance that it pierces the intestines.
Hardufni, nerium oleander, is a shrub that grows to a height of four meters with hard yellow-green leaves and purple flowers. Aside from being bitter, the leaves and flowers of this plant are poisonous, and can kill animals and even people if eaten in large quantities.
Hiltit, Ferula assafoetida, is a perennial herb in the family Apiaceae, that grows to a height of 6-9 feet. It is native mainly to Afghanistan and neighboring countries. The plant grows for a number of years, at which time it flowers and produces fruit, after which it dies. To this day hiltit is recognized as a medicinal plant; resin extracted from its roots is used to develop medicines that are used as powders, creams and pills that are used as treatment for intestinal discomfort and diseases, as well as for strengthening the nervous system. Although it is also used as a spice, large amounts – more than half a gram – could lead to poisoning.
Regarding the Mishnah’s ruling that an animal that ingests poison does not become a terefah but is forbidden to eat for reasons of danger, several of the commentaries argue that this seems to negate the general principle that we learned– that an animal that is injured and will not survive a year is a terefah. Certainly an animal that is poisoned will not survive; why is it not a terefah? The Ra’avad suggests that since the poisoned animal can be treated with medicines, it is not certain to die and is not a terefah; others argue that since there is no immediate terminal injury, even if the animal will certainly die at some later time because of the effects of the poison, it cannot be considered a terefah.