YOU SAID:
Heart disease will come to the cats if they are kept fat.
INTO JAPANESE
猫が太っていると心臓病になります。
BACK INTO ENGLISH
If your cat is fat, you will have heart disease.
INTO JAPANESE
猫が太っている場合、心臓病にかかります。
BACK INTO ENGLISH
If your cat is fat, you will have heart disease.
That didn't even make that much sense in English.