Unlike food, antagonists stay remarkably consistent from fable to fable. The antagonist is almost always a dog, a cat, or a domestic servant or group of servants (usually a cook, a butler, or a maid). In no fable do the mice directly encounter the master or owner of the house explicitly (though a few mention his son). In my analysis, all humans that are not domestic servants are classified simply as "someone" since this is usually how the fable discusses them (IE "all of a sudden, someone opened the door.")
As one might expect, Cats are the most frequent enemy of mice and far more likely to appear alone. No fable yet included mentions specific breeds of cats, but many mention breeds of dogs (Terriers and Mastiffs most frequently, Virgil uses Mastiffs).
One trend I observe that may bear further investigation is that there appears to be a decline in variants that mention servants over time. I have attempted to represent this as follows.
It's possible that what we're seeing here is a once common trope (servants encountering mice in the course of their daily routine) that became less relatable over time. There are several issues with the data represented above, primarily that the sample size is quite small (especially for periods prior to the 18th century). Another is that the date associated with each variant is the date it was published, which in many variants is many years (even a century or more) after it was composed. It will be interesting to see how these numbers change as the collection grows in size and scope.