Cages in the pfapg dataset (data/alpha/paizo/pathfinder_rpg/advanced_players_guide/pfapg_equip.lst, lines 108-112) currently have "TYPE:Goods.Animal" but should have "TYPE:Goods.Animal.Container" and should also have "CONTAINS:1|Animal=1"; though I'm not sure how to restrict that by animal size, they should at least be functional as animal containers.
At revision: 19706-7