They usually struggle to breathe and are overall so much more sickly than any other pure breeds. You might counter argue that other pure breeds are equally unhealthy like dachshunds and back issues, Cocker spaniel's ears, Golden retrievers and lymphoma and labrador retrievers and obesity. The truth is that dachshunds usually don't fail to live to even their 7th birthdays because of their back issues and they normally don't cause as much suffering as bulldogs have to live with day in day out. With cocker spaniels, It's just ear infections and with golden retrievers many of them go into remission and even those who don't usually live longer than bulldogs and have better quality of life. Also, If labrador retrievers get their daily exercise and are not overfed, They won't get obeese.