MB3 96a: Binding the Legs, Tying Together, or Using Other Protective Devices on Animals on Shabbos (305:12-17)

An animal can't wear something that identifies to whom it belongs. Using restraints on animals on Shabbos. Anything that causes discomfort (e.g. a muzzle) can't be put on an animal on Shabbos. Using a seeing-eye dog on Shabbos. Amulets for animals.