YOU SAID:

my dog is a cat that is a horse

INTO JAPANESE

私の犬は馬の猫

BACK INTO ENGLISH

My dog is a cat horse.

INTO JAPANESE

私の犬は、猫馬です。

BACK INTO ENGLISH

My dog is a cat.

INTO JAPANESE

私の犬は、猫です。

BACK INTO ENGLISH

My dog is a cat.