A bull and all other animals are alike as regards falling into a pit, separation from Mt. Sinai, the twofold payments, returning a loss, unloading, muzzling, kilayim, and the Sabbath. The same applies to wild beasts and fowl. If so, why is ox or donkey stat-ed? Because Scripture speaks of the usual.

[If] one brings a sheep into a fold and locks [the door] before it properly, but it gets out and damages, he is exempt. [If] he does not lock [the door] before it properly, and it gets out and damages, he is liable.  [If] it breaks at night, or if robbers break it, and it goes out and damages, he is exempt. Should robbers take it out, the robbers are liable.