My female syrian definitely has more of an odour when she's on heat, and her wee smells different and is a bit more pungent
I'm used to the smell but sometimes I get an especially large waft that puts me off my lunch! I've also noticed on some cycles she doesn't smell different at all, so I think it just depends! I mostly notice changes in her behaviour too with her having a lot more energy and scent marking things more often.