Selective breeding for exaggerated physical traits has created serious inherited health problems in many popular dog breeds.
Brachycephalic breeds including bulldogs, pugs, and French bulldogs live lives of chronic breathing difficulty, exercise intolerance, and sleep disruption. Syringomyelia in Cavalier King Charles Spaniels causes excruciating spinal pain from skulls too small for the brain. Welfare-focused breeding prioritizes health over appearance and avoids extreme conformations.