No, the cat didn’t vanish. Seras just dropped her.

Seras: Aaaugh!

Pip: What is it?

Walter: A chordewa.

Pip: A what?

Walter: A type of vampire, which originated in Bengal. Known to favor cat form, but can be distinguished by an ordinary cat by the abnormal sound.

Also, if one licks you on the lips in cat form, you die soon after.

Pip: Mmph!