Hopefully my response is helpful at all! If you want to have multiple selections using an action filter, you can direct your users to CTRL + Click multiple items which will allow them to see more than one animal. Another way you could accomplish this is by creating a calculated field that combines INDEX() and Animal, and then use that as a quick filter. I've modified your workbook and attached with that solution included.
Is this the kind of functionality you were looking for?
Animals Parameters Tableau.twbx 48.4 KB