Must every case of ritual slaughter include a flow of blood from the neck of the animal?
If a man slaughtered cattle or a wild beast or a bird and no blood came forth, the slaughtering is valid and it may be eaten by him whose hands have not been washed, for it has not been rendered susceptible to uncleanness by blood. Rabbi Simon says, it has been rendered susceptible to uncleanness by the slaughtering.
The simplest explanation for the Mishna is that it is teaching about a case where the person performing the slaughter did not cut the veins and arteries together with the trachea and the esophagus (see above, daf 28). The Mishna teaches that this does not affect the status of the animal as far as the laws of kashrut are concerned, since, as the Ri”d explains, the blood will be removed when the meat is salted or as the Rashba explains, blood is only forbidden once it separates and is no longer absorbed in the meat. The Rambam suggests that the point of the Mishna is to teach that we do not suspect that an animal was already dead or dying just because no blood came out at the time of slaughter.
The Rashba also notes that the Mishna emphasizes that this law is true regarding wild animals and birds, as well as domesticated animals. This is important since the law of kisuy ha-dam – the halakha that requires the blood of the animal be covered after ritual slaughter – applies only to wild animal and birds (see Vayikra 17:13). It is, therefore, important to teach that even if there is no blood to cover, the slaughter is nevertheless acceptable.