YOU SAID:

the dog chewed its own tail

INTO JAPANESE

犬は自分のしっぽを噛んだ

BACK INTO ENGLISH

The dog bit his tail

INTO JAPANESE

犬はしっぽを噛んだ

BACK INTO ENGLISH

The dog bit the tail

INTO JAPANESE

犬がしっぽを噛んだ

BACK INTO ENGLISH

The dog bit the tail