One must keep his animal from working on Shabbat: Shabbat 153a, Pesachim 53a
It is permissible to have an animal do anything which is a Rabbinic prohibition for a friend to do: Shabbat 153b
Putting one's animal in a position where it can graze on uncut grass, or on items which one may not move: Shabbat 122a; Eruvin 79a
"Mechamer" - Leading an animal which is carrying a burden: Shabbat 153b, 153b-154b
The above "Mechamer" as a Prohibition for which the Requisite Warning is for a Death Penalty, not Whipping: Shabbat 154a
Providing Animals to Nochrim
Selling working animals to nochrim, such that they might be used for work on Shabbat: Pesachim 53a, Bechorot 2a-b, 13a
Fining someone who sells a working animal to a nochri, out of concern that he might sell it just before Shabbat and, in the process, cause the animal to carry a burden on Shabbat [mechamer]: Bechorot 3a
Selling damaged/non-working animals to nochrim: Pesachim 53a; Bechorot 2a-b
Selling a horse [rather than an animal that carries burdens] to a nochri: Shabbat 94a, Pesachim 53a; Bechorot 2a
Selling an animal fetus in utero to a nochri: Bechorot 2a-b
Determining Law by the Local Custom in selling non-working animals to Nochrim: Pesachim 53a