I took Chewy in a carrier on JetBlue. On the way out to CA, they were kind of strict, but on the way back they let me take him out. The flight attendants thought he was cute! I think it all depends on the situation and the crew

. I think you can have your big dog with you in a seat if you pay for the cost of that seat and only a few airlines do it...I'm not sure what the stipulations are though.