YOU SAID:
My dog think he is more beautiful that me
INTO JAPANESE
私の犬は彼が私よりも美しいと思っています
BACK INTO ENGLISH
my dog thinks he's prettier than me
INTO JAPANESE
私の犬は自分が私よりかわいいと思っている
BACK INTO ENGLISH
my dog thinks he's prettier than me
That didn't even make that much sense in English.