DEUT1430 Biblical consideration for animals was the basis for the following laws: … An animal which works in an operation that exposes it to food which is eaten by animals must not be muzzled [this verse]. In such circumstances, the prevention of the animal from eating is an act of cruelty. Josephus (1st cent.) places this injunction on a moral plane of equity and fairness. "It is not just to restrain our fellow-laboring animals… of the fruit of their labor" (Antiq. 4:8). The required degree of animal care reached a noble dimension in rabbinic literature. It is forbidden to buy animals or fowl unless preparation of food for their sustenance has been made in advance. (Jer. Yevamot 15:3). Rav (3rd cent.) is the author of a rule which stipulates that owners must feed their animals first before sitting down to enjoy their own meals (Berachot 40a). It is important to bear in mind that Rav's rule applies exclusively to owners, since they bear a responsibility for the feeding of their cattle. No such preference is proper when one has to satisfy the needs of a hungry guest and his hungry animal. The interest of man must precede that of an animal. The major concern for the welfare of man has led the rabbis to discourage the raising of dogs. A dog which attacks or frightens strangers will inevitably deter the poor from entering a home for the purpose of soliciting charity or help (Shabbat 63a). For the same reason the rabbis urged that all dogs be kept on a leash (Baba Kama 79b).