Tosefta for Chullin 99:1

Among the [wounds to] limbs that [render an animal] disqualified [are] a limb that dangles from the animal and does not have enough [flesh between the animal and the dangling limb] to permit it to heal itself; flesh that dangles from an animal in insufficient quantity to permit it to heal itself; a broken bone that juts outside [the body of the animal] and the hide and flesh [around the break] are not sufficient to encircle [the broken limb]. How is it done? He takes [the dangling portion] and discards it, and [as to] the remainder, behold, it is permitted. Among the [wounds to] fetuses that are disqualified at four [months] for a small animal and eight [months] in a larger animal [are a fetus] that has two backs or that has two spines. Since it cannot remain [living] with these [deformities], it is disqualified. And these are valid (see Hul. 3:2): In livestock, a punctured esophagus or an esophagus torn lengthwise, these are valid. [An animal with] a broken spine but the majority of its spinal cord was not severed is valid. [If] the liver was removed but there remained a sufficient quantity to permit healing, it is valid. [If] the lung was punctured but the membrane remained, it is valid. [If] her womb was removed, it is valid. [If] the liver is wormy, it is valid. [With regard to] this halacha, the people of Asia Minor (see Hul. 48a:1 ("בני עסיא")) ascended three times (alt., "during three festivals") to Yavneh [to inquire about its status], and on the third time (alt. "festival") they ruled that it was valid. Rabban Shimon ben Gamaliel says, small intestines (דקין) that were perforated, but afterwards became stopped up again, are valid. A needle that is found [after the slaughter] in the thickness of the reticulum (Hul. 50a:11) -- when it sticks out of (lit., "is seen from") one side, it is valid, and from two sides, it is disqualified. If a drop of blood is [found] in its place (i.e., on the needle, see Hul. 50b:11-51a:1 (Steinsaltz)), then it is certain that [the perforation existed] before the slaughter, and if there is no blood [found] in its place (i.e., on the needle), then it is certain that it occurred after the slaughter. If a scab covered the opening of the wound, it is certain that [the perforation occurred] three days before the slaughter, [but] if a scab did not cover the opening of the wound, [the status is uncertain and] the burden of proof rests on the claimant (Hul. 51a:2 (Steinsaltz)).