YOU SAID:

My dog is old and fat and cannot eat by himself

INTO JAPANESE

私の犬は古くて太っていて、一人で食べることができません

BACK INTO ENGLISH

My dog is old and fat and can't eat alone

INTO JAPANESE

私の犬は古くて太っていて一人で食べることができない

BACK INTO ENGLISH

My dog is old and fat and can't eat alone