24. If an animal has eaten too much vetch [for example], and is in pain, one may make it trot in the courtyard on Shabbos so that it will become tired, and be relieved of its pain. If it overheats due to blood problems, one may lead it into water so that it will cool off (1). If there is a possibility that it will die unless its blood is let, one may tell a Gentile to do so (2). Other remedies should also be administered by a Gentile.
(1) The Sages prohibited the administration of certain remedies on Shabbos, however, the prohibition does not apply to animals (Mishna Berura 332:5).
(2) The Mishna Berura (332:6) rules that a Gentile may be used even if there is no danger to an animals life, as long as it is suffering in some way.