The answer: it is defective with a defect worse than one-eyedness. This is an argument from stronger analogy. The correct view, therefore, is that a blind animal is not valid.
His statement, “the emaciated animal”: this is the thin animal that has no marrow. With extreme emaciation, the marrow disappears, leaving only a red substance inside the bone. Such an animal is not valid, because it is weak in body and unpleasant in appearance. As for an emaciated animal that still has marrow—that is, one whose emaciation has not reached the interior of its bones—it is valid, because the Messenger, peace and blessings be upon him, said: “the emaciated animal that has no marrow.” The scholars said that “has no marrow” means that it contains no marrow; niqy means marrow.
Those with experience say that when spring arrives suddenly while the sheep are emaciated, and they then graze on the spring pasture, they develop fat before marrow forms within them. An animal that has put on fat but has not yet developed marrow is valid, because the Prophet, peace and blessings be upon him, said, “the emaciated animal that has no marrow.” This animal is no longer emaciated; rather, it is fat, but the fat has not yet entered the bones for marrow to form. We therefore say that the Prophet, peace and blessings be upon him, described it by two characteristics: that it is emaciated and that it has no marrow. Since this one is not emaciated, it is valid.
His statement, “the lame animal”: what is meant is one whose lameness is plainly evident, based on the Prophet’s statement, peace and blessings be upon him: “the lame animal whose limp is clearly apparent.” It is the animal that cannot walk alongside a sound one. Its lameness is thus evident. But if it limps while still being able to walk alongside a sound animal, then its lameness is not evident. Nevertheless, the more complete and sound the animal is, the better.
The wisdom behind this is that, if an animal is in such a condition, it may fall behind the other animals while grazing and fail to eat enough. Consequently, it will generally be emaciated.