I think it’s that the common traits overlap somewhat: In the context/understanding that everyone (male or female, human or animal) has both masculine and feminine aspects. Cats tend to be more sensitive, dignified, cautious, concerned with cleanliness, elegant, quiet. hinting, teasing, and perhaps some other things that are also what people tend to think of as feminine. Dogs tend to be more direct, messy, loud, aggressive, and perhaps some other things that are also what people tend to think of as masculine.