Bava Kamma 51 - Shabbat December 23, 11 Tevet

A bor of less than ten handbreadths does not kill. If so, why did Rav Nachman rule that an animal that had fallen into a pit less than ten handbreadths (six) and was then slaughtered, was not kosher for eating as he must have been a treifa (going to die anyway)? Rava brings our Mishna and two other tannaitic sources to raise a difficulty with Rav Nachman's ruling. In cases where two people own the bor or a responsible for it, who assumes responsibility? How is it possible to have a bor owned by two people? At what point does the responsibility shift from one to the other?