My parents have a pug. The poor thing's had a host of issues. Poor breathing is one thing, but she also had seizures early in life(They seem to have gone away). She got cancer in one eye(Didn't lose the eye, but there's some scarring on it). Weird growths on her legs too that had to be removed. She also developed allergies that she currently takes medication for because if she doesn't she'll scratch until she starts tearing skin.
And despite all that she still seems healthier than most pugs I see. My dad loves that dog, but he's said he'd never get another one.