Yoma, Chapter Eight, Mishnah Six
After teaching in the previous mishnah that serious health concerns override the observance of Yom Kippur, our mishnah expands this message to include other prohibitions as wellif a persons health is in danger he may do things otherwise prohibited.
1) If one is seized by a ravenous hunger, they feed him even unclean things until his eyes light up [and he returns to health].
2) If one was bit by a mad dog, they do not feed him the lobe of its liver.
a) But Rabbi Matia ben Harash permits it.
3) Moreover Rabbi Matia ben Harash said: if one has pain in his throat, they may drop medicine into his mouth on Shabbat, because it is a possibility of danger to human life and every potential danger to human life overrides Shabbat.
Section one: Here we learn that if a person is overtaken by a ravenous hunger, one that if not satisfied might put him into physical danger, they may feed him anything, even non-kosher food. As I said in yesterdays mishnah, this mishnah is addressed to the religious fanatic who would rather endanger his life or the life of another rather than transgress the commandments. The mishnah is saying that this is prohibited because the value of life is greater than that of the commandments.
Section two: Here the mishnah expresses a limit to the previous principle. Evidently, there was a belief in the time of the Mishnah that if one was bitten by a rabid dog, eating its liver-lobe would serve as a cure. Most rabbis didnt believe that this cure really worked and hence they should not give him the liver-lobe to eat. Saving a life overrides the commandments, but only if that which is done really has a chance of working. However, Rabbi Matia permits even this. There are two different explanations for his opinion. The first is that Rabbi Matia holds that eating the liver of the rabid dog is really an effective cure. The other, in my opinion more convincing explanation is that since the bit person thinks this cure is effective, the fact that it offers him psychological relief is enough for Rabbi Matia to permit it.
Section three: Rabbi Matia goes a step further and says that anyone who feels pain on Shabbat, and who thinks that the pain might be an issue of life and death, others must give him medicine on Shabbat. As we learned frequently when we studied Shabbat, medicine is prohibited on Shabbat. Here we learn that this is true only if it is not a potential threat to a persons life. If there is danger to ones life, then it is permitted, and indeed mandated to heal the person on Shabbat.
 Julius Preuss, Biblical and Talmudic Medicine, p. 196, writes, To treat the bite of a mad dog, the heathen physicians of antiquity, in general, as well as many primitive peoples today, gave the patient certain pieces of the liver of the mad dog to eat. Preuss refers to a number of Greco-Roman authors. If you wish to try this at home, know that most of them recommend the liver be roasted. Chopped liver is not recommended.