Shulchan Arukh, Orach Chayim 522/שולחן ערוך·אורח חיים תקכ״ב

1A few things that are forbidden to be carried on Yom Tov, and there are 4 Simanim: The blind man may not leave with his stick nor the shepherd with his sack (and the law of a disabled person is the same on a holiday as it is on Shabbat, see above chapter 301 paragraph 17).

2Neither a man nor a woman may go out in a [carried] chair. If many people need him, it is permitted, and he may be carried on the shoulders, even in a litter (or a canopy).

3Someone whose legs have shrunk (meaning that they have become shorter) can leave with his stick.

4We do not lead an animal with a stick.