YOU SAID:
my horse is a good horse
INTO JAPANESE
私の馬は良い馬です。
BACK INTO ENGLISH
My horse is a good horse.
INTO JAPANESE
馬は死んでいる
BACK INTO ENGLISH
My horse is dead.
INTO JAPANESE
馬は死んでいる
BACK INTO ENGLISH
My horse is dead.
That didn't even make that much sense in English.