Contributors: Philip Lhermette, Elise Robertson

 Species: Canine   |   Classification: Techniques

Introduction Requirements Preparation Procedure Aftercare Outcomes Further Reading



  • Evaluation of laryngeal structure and function.
  • Investigation of:
    • Phonation changes (loss of bark or purr).
    • Gagging or coughing during eating or drinking.
    • Stridor.
    • Increased respiratory effort, noisy breathing or cough.
    • Exercise intolerance.
    • Elongated soft palate Soft palate: elongated : should be anticipated and treated at the time of scoping if possible (resection Soft palate: resection ).
    • Laryngeal mucosal edema.
    • Edematous/everted laryngeal saccules (lateral ventricles).
    • Laryngeal paralysis Larynx: paralysis : may be unilateral or bilateral.
    • Laryngeal collapse Larynx: disease overview : a life threatening complication of chronic upper airway obstruction.
    • Laryngeal neoplasia Larynx: neoplasia : lymphoma, squamous cell carcinoma, other carcinomas are the common types.
    • Epiglottic entrapment: secondary to other inspiratory problems, typically very intermittent.


  • Technically easy procedure.
  • Any combination of instruments can be used as long as adequate illumination of larynx is generated.


Time Required



  • Laryngoscopy can be performed in a matter of minutes. Depends of experience of endoscopist - approximately 1-2 minutes

Decision Taking

Risk assessment

  • Low risk unless patient unstable prior to general anesthesia or in respiratory crisis.
  • See complications.



Veterinarian expertise

  • Medium.

Anesthetist expertise

  • Medium.
  • Needs to be prepared for potential respiratory complications associated with induction, maintanence and recovery from chemical restraint.

Nursing expertise

  • Good level of competence required for assisting with and monitoring anesthetic.

Materials Required

Minimum equipment

  • Oral speculum.
  • Standard intubating laryngoscope and appropriate sized blades.
  • OR overhead examination light, pen light, and common wooden tongue depressor to depress the epiglottis.
  • Appropriate sized endotracheal tubes Endotracheal intubation in case required to secure a patent airway during anesthesia or recovery.
  • Appropriate sized tracheostomy tubes in case required for respiratory compromised patients on recovery (laryngeal paralysis, edema, or masses).

Ideal equipment

  • Oral speculum.
  • Standard intubating laryngoscope.
  • 2.7 or 2.8 mm or 5 mm rigid telescope or 2.5 or 3.5 mm flexible endoscope Flexible endoscopy.
  • video monitor for better visualization and for case documentation (still images and video).
  • In larger dogs (>7.5 kg) a 5.2 mm bronchoscope or 5 mm rigid endoscope can be used.

Other requirements

  • Know what normal anatomy and normal anatomic variations.



  • The patient must be under a light plane of anesthesia when assessing laryngeal function:
    • If too deep, the larynx appears paralysed.
  • Best not to give patient a narcotic or synthetic narcotic before laryngoscopy:
    • Can induce panting, hypoventilation, and abolish cough reflex.
  • Injectable anesthetics most typically used for laryngoscopy.
  • A light plane of anesthesia using intravenous propofol Propofol to effect (1 to 4 mg/kg IV) or alfaxalone 2-3 mg/kg to effect Alphaxalone (Alfaxan) :
    • Given slowly over 30 seconds to 2 minutes, to effect.
    • Supplemental mask oxygen.
  • Ketamine and diazepam used in combination is an excellent choice in the cat:
    • Intravenous propofol to effect can be used as an alternative to ketamine and diazepam in the cat.
    • Topical 1% lidocaine Lidocaine may occasionally be needed to decrease reflex responses during the procedure (most common in feline patients).

Dietary Preparation

  • Food should be withdrawn for 6-12 hours to minimize risk of aspiration during the examination.


  • Light sedation.

Other Preparation

  • Preanestheic laboratory tests can be performed as indicated by the patient's age and health status.



Step 1 - Anatomic examination

  • GENTLY depress the epiglottis from the visual field Endoscopy introduction of esophagoscope over larynx.
  • Gently elevate the soft palate as required.
  • Pull tongue forward to aid in visualization.
  • Soft palate should not extend to the larynx or interfere with respiration.
  • Evaluate the cricoid, thyroid, and arytenoid cartilages.
  • Evaluate the vestibular folds, vocal folds, laryngeal saccules, epiglottis, and aryepiglottic folds:
    • Normal mucosa light pink and superficial vessels may be visible.
    • Secretions minimal near the normal laryngeal vault.
    • Abnormal findings:
      • Mucosal hyperemia and edema.
      • Excessive secretions.
      • Redundant pharyngeal mucosa.
      • Elongated soft palate, everting laryngeal saccules and accumulation of salivary secretions are common findings in dogs with brachycephalic syndrome.
      • Laryngeal collapse loss of cartilage rigidity secondary to upper airway obstruction in brachycephalic syndrome Brachycephalic airway obstruction syndrome.
      • Laryngeal webbing and granuloma formation secondary to previous surgery or trauma.
      • Both can result in stenosis of glottic lumen.
      • Less commonly, a pharyngeal or laryngeal rannula, tumor, or foreign bodies.

Step 2 - Functional examination

  • Monitoring laryngeal adduction, abduction and symmetry of movement:
    • Normal patients arytentoid cartilages should abduct during inspiration and adduct toparamedian position during expiration.
  • If laryngeal motion appears abnormal ruling out laryngeal paralysis:
    • Doxapram hydrochoride Doxapram 0.5-1.0 mg/kg IV administered:
      • Increases rate and depth of inspiration.
      • Overrides the potentially depressant effects of anesthesia on laryngeal motion.
  • Important for assistant toannouncephase of respiration with each breath and therefore not confuse normal motion with paradoxical motion which can indicate complete laryngeal paralysis:
    • Left, right, or both arytenoid cartilages may have decreased motion (paresis) or not move at all (paralysis) during inspiration.
    • Unilateral and bilateral laryngeal paresis and paralysis occurs in dogs, rarely in cats.
    • Most dogs with laryngeal paralysis have erythematous vocal folds due to turbulent air flow.
    • Cats with laryngeal paralysis may appear soft and floppy with fluttering on expiration.




  • Close observation on anesthetic recovery if anatomic or functional laryngeal disease is diagnosed:
  • Breathing rate, effort and depth.
  • O2 saturation using pulse oximetry Anesthetic monitoring: pulse oximetry.


  • Usually not required.

Antimicrobial therapy

  • Rarely required.

Potential complications

  • Relatively low risk procedure.
  • Stimulation of larynx may provoke a very strong vagal response that may result in profound bradyarrythmias:
    • Administering anticholinergic medication before anaesthesia is induced largely prevents this.
  • Manipulation of laryngeal mucosa can cause additional mucosal irritation, edema and potentially further narrowing of the airway (complication more common in cats):
    • It is ESSENTIAL for the operator to be very gentle when manipulating this area thus reducing chances of complications due to laryngeal edema and occlusion.
  • Some patients with laryngeal disease may have great difficulty maintaining a patent airway during postanesthetic recovery phase:
    • Endotracheal and tracheostomy tubes and instruments should be available (in suspected cases).



  • As directed by underlying disease process.

Follow up

  • As directed by underlying disease process.


Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Creevy K (2009) Airway Evaluation and Flexible Endoscopic Procedures in Dogs and Cats: Laryngoscopy, Transtracheal Wash, Tracheobronchoscopy, and Bronchoalveolar Lavage. Vet Clin North Am Small Anim Pract 39 (5), 869-880 PubMed.
  • Noone K E (2001) Rhinoscopy, Pharyngoscopy, and Laryngoscopy. Vet Clin North Amer Small Anim Pract, 31 (4), 671-689 PubMed.

Other sources of information

  • Padrid P A (2011)Laryngoscopy and Tracheobronchoscopy of the Dog and Cat.In: Tams T R, Rawlings C A (eds)Small Animal Endoscopy, St Louis, Elsevier Mosby.
  • Levitan D, Kimmel S (2008)Flexible endoscopy: respiratory tract.In: Lhermette P, Sobel D (eds)BSAVA Manual of Canine and Feline Endoscopy and Endosurgery, Quedgeley, British Small AnimalVeterinary Association.