Abu Ushara reported from his father who said that he asked, “0 Messenger of Allah, is the slaughtering only from the throat and upper pait of the breast?” He said, “If you strike the spear on its thigh then it is enough.’ Ahmad ibn Mani reported from Yazid ibn Harun that this was allowed in cases of necessity.
[Abu Dawud 2825, Nisai 4420]