Selective breeding for extreme physical characteristics has created severe welfare problems in many popular dog breeds, with brachycephalic airway syndrome the most significant example.
Breed-specific welfare problems represent welfare compromise built into the genetics of millions of companion animals - conditions that are not accidents of illness but predictable consequences of deliberate breeding choices. BOAS in brachycephalic breeds means millions of dogs worldwide are unable to breathe normally, experiencing varying degrees of respiratory compromise during normal activity, rest, and sleep. The sleep-disordered breathing documented in severely affected individuals represents continuous nocturnal welfare compromise. The welfare harm is amplified by the normalization of heavy breathing in these breeds - owners who have never seen the breed breathe without snorting may not recognize it as abnormal. Breeding reform requires changing cultural preferences that have made extreme brachycephaly a desirable trait.