Intubation provides better airway control than a face mask and minimizes the risk of aspiration. This is especially important
for complex and prolonged procedures, when complications such as respiratory obstruction and hypoventilation are more likely
to occur. Rabbits and rodents are difficult to intubate. They have a large tongue, large molars, a small larynx, and a soft
palate that easily obscures the epiglottis. While intubation of small mammals is difficult, it should be the routine standard
of care all patients as long as it can be done quickly and safely.
Endotracheal intubation is the placement of a tube that extends from the oral cavity into the trachea. It is indicated for
the administration of oxygen and inhalation anesthesia, to ensure a patent airway in unconscious patients, to provide ventilatory
assistance, and to provide a conduit into the trachea to permit diagnostic and therapeutic measures (e.g. endoscopy, tracheal
wash, direct instillation of medications).
Various intubation techniques have been suggested for small mammals. Some of these require specialty equipment, and all require
practice. Intubation methods can be divided into those that are performed blind or with visualization of the larynx.
By properly positioning the head and neck, the pathway from the oropharynx to the trachea is straightened so that an endotracheal
tube can be placed without direct visualization of the larynx. This is possible with the aid of laryngeal palpation, patient
response (i.e. coughing, gagging), and listening for patient respiration through the endotracheal tube itself. Under special
circumstances, a transtracheally-placed catheter may be used as a guide.
Divided into direct visualization and indirect visualization of the glottis.
• Direct Visualization- Visualization of the larynx is aided by hyperextension of the head and neck. Usually an assistant
must open the mouth with gauze placed around the upper and lower incisors, or an oral speculum is used. A small bladed laryngoscope
(e.g. Miller 0 neonatal laryngoscope blade) is used to depress the tongue and elevate the soft palate. Once the vocal folds
are visualized, the tube is placed. An atraumatic stylet (such as a polypropylene catheter) can be placed through the tube
so its tip extends beyond the end of the endotracheal tube. Being narrower than the endotracheal tube, the stylet tip will
fit easily into the trachea and help to guide the tube through the vocal folds. A canine otoscope can be used instead of
a laryngoscope in smaller patients. After adequate visualization is achieved, a 5 French polypropylene urinary catheter is
guided down the otoscope between the vocal folds and advanced into the trachea. At this point, the otoscope is removed and
the tracheal tube is threaded over the catheter and into the larynx. The catheter guide is then removed.
• Indirect Visualization- Visualization of the trachea can also be achieved using an endoscope. The endoscope is
positioned so the larynx is in view, and an endotracheal tube is passed parallel to the scope and into the trachea. Further,
with some scopes it is possible to put endoscope directly inside the endotracheal tube like a stylet, and to visually guide
the scope/tube assembly into the trachea.
Endotracheal tube size/style for selected species
• Ferret: 2-2.5mm ID (Cole or Murphy)
• Rabbit: 2-3.5 ID (Cole or Murphy)
• Prairie dog: 2-2.5mm ID (Cole or Murphy)
• Guinea pig: 8-fr (urinary catheter), 2-2.5mm ID (Cole or Murphy)
• Hedgehog: 1.5 mm ID (straight silicone)
• Sugar Glider: 1.5 mm ID (straight silicone)
• Chinchilla: 8-fr (urinary catheter)
• Rat: 14ga (IV catheter)