YOU SAID:

My dog needs to go outside because he is not trained.

INTO JAPANESE

私の犬は訓練されていないので外に出る必要があります。

BACK INTO ENGLISH

My dog is not trained and needs to go outside.

INTO JAPANESE

私の犬は訓練されておらず、外に出る必要があります。

BACK INTO ENGLISH

My dog is not trained and needs to go outside.