Sforno on Exodus 22:12/ספורנו על שמות כ״ב:י״ב

1יביאהו עד, we already explained that whenever the Torah uses the word עד in the singular mode what is meant are two witnesses who are acceptable to the court. אם טרוף יטרף, by some wild beast; presumably someone did witness the occurrence seeing there must have been other shepherds in the vicinity. What kind of testimony is expected of these witnesses?

2הטרפה, that the situation in which the animal had been mauled or eaten was the kind of accident which the shepherd guarding it could not have been prevented by exercising greater care.

3לא ישלם, the shepherd does not have to make restitution. If, however, the predators had eaten the animal under discussion due to insufficient supervision on the part of the shepherd, the shepherd has to make restitution. (compare Baba Metzia 93) In determining a reasonable fight which the shepherd has to put up against predators, Rashi quoting the Mechilta says that a solitary wolf is not something against which the shepherd is defenseless, neither are two dogs. Naturally, smaller animals and rodents are not considered as posing a threat to man.