Yosef Karo

“ With small livestock, and with large or small game, whether it extents its its foreleg and retracts it, or extends its leg even without retracting it, or just flexes its leg, behold it's convulsion and is permitted. ”

“ But this matter is not a prohibition, rather the more one takes this stringency on himself the more praiseworthy.
גדולי החכמים לא היו אוכלים מבהמה שממהרים ושוחטים כדי שלא תמות ואע"פ שפירכסה בסוף השחיטה. ”