YOU SAID:

a dog is a dog except when the dog is a cat that is a dog

INTO JAPANESE

犬は、犬が猫である場合を除き、犬です

BACK INTO ENGLISH

A dog is a dog unless the dog is a cat

INTO JAPANESE

犬が猫でない限り、犬は犬です

BACK INTO ENGLISH

A dog is a dog unless it is a cat

INTO JAPANESE

犬は猫でない限り犬です

BACK INTO ENGLISH

A dog is a dog unless it is a cat