Antony uses the word cur rather than dog to describe Casca because he has contempt for casca and is insulting him.
This is often referred to as an inferior dog with unfriendly and aggressive characteristics.
Antony didn't like Casca which was why he insulted by describing him as a cur in this scenario.
Read more about Connotation here https://brainly.com/question/14905866
#SPJ4