Considering that mages will typically have int +2/+3, I don't see an animal with int -3 as being a fulfilling peer that could compete with a spouse, especially if the animal lacks vocal cords and therefore the ability to speak coherently. At best it'd be like a child.
There is obviously the option of finding a CrAn mage that knows how to stat boost and convince/pay them to up the Int of the familiar, which is probably, in the long run, a good Vis-investement. Also it'd make for an in-game story as such Magi are probably in high demand...