YOU SAID:

i know what many cats are but who might a dog be

INTO JAPANESE

私は猫が何匹か知っていますが、犬は誰でしょうか

BACK INTO ENGLISH

I know some cats, but who are the dogs?

INTO JAPANESE

私は猫を何匹か知っていますが、犬は誰ですか？

BACK INTO ENGLISH

I know some cats, but who are the dogs?