YOU SAID:

There was a cat eating a horse in my backyard yesterday evening.

INTO JAPANESE

昨日の夜私の裏庭で馬を食べる猫があった。

BACK INTO ENGLISH

Cats that eat a horse in my back yard last night.

INTO JAPANESE

最後の夜私の裏庭で馬を食べる猫。

BACK INTO ENGLISH

Cats eat horses in my back yard last night.

INTO JAPANESE

猫は、最後の夜私の裏庭で馬を食べる。

BACK INTO ENGLISH

Cats eat horses in my back yard last night.