Perhaps the "big cat" example is just not poetic enough to fit with "so"? It doesn't sound as "right" as the other "so" examples above, although it doesn't sound completely wrong to me either!
How about this instead:
"O cease!" exclaim'd Dame Gurton straight,
"Has my poor puss been torn away?
Alas! how cruel is my fate,
How shall I pass the tedious day?
Where can her mourning mistress find
So sweet a cat? so meek, so kind!
So keen a mouser, such a beauty,
So orderly, so fond, so true,
That every gentle task of duty
The dear domestic creature knew! http://digital.library.upenn.edu/women/robins...