Shulchan Arukh Yoreh De'ah · Siman 17

English

Seif 1 When one slaughters a healthy animal and after slaughtering it does not make convulsive movements, it is permitted. However regarding an animal that is dangerously ill, i.e., one which cannot maintain itself when others cause it to stand it up, even if it eats the food of healthy animals. If such an animal is slaughtered and does not make any convulsive movements at all, it is a nevelah and one is liable for lashes [for partaking] of it. If it makes convulsive movements, it is permitted. The convulsive movements must be made at the end of the slaughter. If they are made at the beginning, they are of no consequence. What is meant by convulsive movements? For a small domesticated animal and for both a small and a large wild beast, the intent is that it extended its foreleg and returned it, extended its hind leg even though it did not return it, or merely bent its hind leg. This is considered a convulsive movement and [the animal] is permitted. If, however, it merely extended its foreleg and did not return it, it is forbidden. This movement is merely a result of the expiration of the soul. With regard to a large domesticated beast, if it either extended its foreleg or its hind leg without bending it or bent its foreleg or hind leg without extending it, it is considered as a convulsive movement and it is permitted. If, however, it neither extended or bent its foreleg or its hind leg at all, it is considered as a nevelah. With regard to a fowl, even if it only blinked its eyelid or swatted its tail, it is considered a convulsive movement.

English

Seif 2 When one slaughters an animal that is dangerously ill at night and does not know whether or not it made convulsive movements, it is forbidden, because of the possibility that it is forbidden as nevelah.

English

Seif 3 Our great sages would not partake would not eat of an animal which people were hurrying to slaughter before it died, even if it made convulsive movements after being slaughtered. This is an issue that does not involve a prohibited act. Nevertheless, if one desires to accept this stringency upon himself it is considered praiseworthy.