YOU SAID:

I'm struggling to breath as the black dog lies across my chest

INTO JAPANESE

黒い犬が胸を横切って横たわっているので、私は呼吸に苦労しています

BACK INTO ENGLISH

I'm having a hard time breathing because a black dog is lying across my chest

INTO JAPANESE

黒犬が胸に横になっているので呼吸が苦手です

BACK INTO ENGLISH

I'm not good at breathing because the black dog is lying on my chest

INTO JAPANESE

黒犬が胸に横たわっているので呼吸が苦手

BACK INTO ENGLISH

I'm not good at breathing because the black dog is lying on my chest