When Stewie is listening to Buzz Killington, at the end of the sketch, he grabs his nose and sighs. This is the same thing Peter does during an episode where he has to listen to him as well.
Because Brian was blamed for causing the Puerto Rican girl to cry after Stewie points out her bad leg after Glenn warned Brian not to do so he most likely added it to his list of reasons why he hates Brian. It's not mentioned, however, when Quagmire lists his faults in Jerome Is the New Black (2009).
Brian is said to be eight years old. In dog years he would be about 45 then added with drinking and the smoking Lois's first estimate of his age is more accurate at 56.