So I was playing around with some ideas and one that I got was having an Eldritch Guardian/Mutation Warrior, with the intent on having my goat familiar imbibing my mutagen. Under normal circumstances this wouldn't work; my goat is obviously not an alchemist, so he's not going to benefit from drinking a mutagen. However, it got me thinking: is it possible to have a non-humanoid companion (such as an eidolon, familiar, or animal companion) treated as having a class for some purpose, such as the above example of allowing it to imbibe mutagens?
Only with Leadership.
So essentially it's only possible with a cohort. That's a shame, but not unexpected. Thanks!