The embodiment of a "nagging mother-in-law", she often frustrates Horace Horsecollar, although she is usually completely oblivious to this. Like her daughter, she can be very persuasive, and always tries to get things her way. She does not hesitate to express her disapproval of anything, and this criticism is usually aimed at Horace.
She regularly comes to visit Clarabelle and Horace, much to Horace's dismay. She has a tendency to hand out gifts both Clarabelle and Horace hate, such as an ugly painting, and a lamp she only gifted because she had gotten bored with it herself. She does not approve of nor like Horace and the feeling is more than mutual. Her relation with Horace's father isn't great either. Maw Cow compliments all of her daughter's accomplishments and talents, although she insists it's because her daughter takes after her, and stresses that she herself is the origin of her daughter's talents ("She got that from me!").
- Although it is never explicitly stated, it is implied that she is widowed, as she speaks of her husband (Clarabelle's father) in the past tense.
- She is 65 years old.
- Her original Dutch name, Moe Koe, is a play on words, "Moe" being both an informal nickname to refer to one's mother (similar to "Maw"), and also the Dutch spelling of "moo", the onomatopoeic sound a cow makes.