I have one doubt about Rego Animal guidelines based upon rego mentem and "mental" manipulation on animals, are this spells/effects affected by the size of the Individual beasts?
To some effects i think that the Circle Objective cover any animal's size thankst to be in the circle.
IIRC Mentem does not have size. If you have an intelligent whale, you could cast a Reme spell on it without any problems or size modifiers. So, if you are using a ReAn equivalent to a ReMe effect I would rule that it does not have a size modifier either.