YOU SAID:

Walking my dog and it turned into a cat

INTO JAPANESE

私の犬を歩くと、それは猫になった

BACK INTO ENGLISH

As I walked through my dog, it became a cat

INTO JAPANESE

私は私の犬を歩いていると、それは猫になった

BACK INTO ENGLISH

When I was walking in my dog, it became a cat

INTO JAPANESE

私が私の犬の中を歩いていたとき、それは猫になった

BACK INTO ENGLISH

It was a cat when I was walking in my dog

INTO JAPANESE

私が犬の中を歩いていたときは猫だった

BACK INTO ENGLISH

It was a cat when I was walking in the dog

INTO JAPANESE

私が犬の中を歩いていたときは猫でした

BACK INTO ENGLISH

It was a cat when I was walking in the dog