Rabbit respiratory system — an obligate nasal breather
Overview of the rabbit respiratory tract — a larynx seated behind the soft palate that makes breathing near-exclusively nasal, constantly twitching nostrils, and a small chest driven mainly by the diaphragm.
General educational reference only — not clinical or veterinary advice. Anatomy varies between individual animals; consult a licensed veterinarian for any health concern.
Obligate nasal breathing
Rabbits are obligate nasal breathers. At rest the epiglottis sits dorsal to the soft palate, locking the larynx into the nasal airway and sealing off the route through the mouth, and the long incisors, narrow oral cavity and large tongue leave little alternative path. Air therefore normally enters and leaves through the nose alone. The nostrils twitch rhythmically many times a minute as the rabbit samples the air, a movement that quickens with alertness and nearly stops at complete rest.
A compact chest
The thorax is small relative to the large abdomen, and much of it is occupied by the heart and by the thymus, which in rabbits persists into adulthood rather than shrinking away after youth. With the ribcage contributing comparatively little movement, breathing is driven mainly by the diaphragm, and abdominal organs pressing forward against it influence how freely the lungs fill. Resting breathing is correspondingly quick and shallow.
Airway and lungs
Air warmed and filtered in the nasal cavity passes the larynx into a fairly narrow trachea, which divides into bronchi serving lungs of unequal size: the left lung has two main lobes and is smaller, sharing space with the heart, while the right has four, including an accessory lobe. As in other mammals, the airways end in alveoli, where gas exchange with the blood takes place.
