Brachycephalic literally means "short-headed." The flat-faced conformation comes with a package of anatomical features collectively called brachycephalic obstructive airway syndrome (BOAS): narrow nostrils, elongated soft palate, narrow trachea, and sometimes laryngeal collapse.

Practical implications: reduced ability to cool by panting (high heatstroke risk), louder breathing especially when excited or sleeping, exercise intolerance, susceptibility to respiratory infections, and higher anaesthetic risk. Many brachycephalic dogs benefit from surgical correction (BOAS surgery) which can be life-changing.

Brachycephalic cats — Persians, Himalayans, Exotic Shorthairs — face similar but less severe airway issues, plus eye problems from shallow sockets and dental crowding from short jaws.

If you own a brachycephalic breed, the key adaptations: harness instead of collar, no exercise in heat (restrict above 22–25°C), maintain lean body weight, regular vet airway assessment, and a low threshold for vet visits when breathing changes.