Lecture 33- Clinical Signs of Laryngeal and Pharyngeal Disease

Key anatomy structures (pharynx)

Hard palate, soft palate, palatopharyngeal arches, nasopharynx, ventral nasal meatus, oropharynx, larynx, laryngopharynx, epiglottis.

Key anatomy structures (larynx)

Arytenoid cartilage, corniculate/cuneiform processes, aryepiglottic fold, vocal/vestibular folds, epiglottis, thyroid/cricoid cartilages, associated muscles.

Hallmark signs of laryngeal disease

Respiratory distress + stridor.

Additional laryngeal disease signs

Gagging, coughing, voice change (inconsistent), acute airway obstruction.

Compensation in early laryngeal obstruction

Reduced activity to minimize respiratory effort.

Crisis triggers in laryngeal disease

Overheating, excitement, exercise → increased respiratory effort → collapse.

Paradoxical motion definition

Soft tissues pulled into airway during inspiration due to negative pressure → worsens edema/obstruction.

Respiratory pattern in laryngeal disease

RR normal–slightly elevated (30–40/min) despite distress; prolonged labored inspiration; passive expiration but edema may obstruct.

Aspiration pneumonia association

Common with laryngeal paralysis; signs: cough, lethargy, anorexia, fever, tachypnea, abnormal lung sounds.

DDx for laryngeal disease

Paralysis, neoplasia, obstructive laryngitis, laryngeal collapse, web formation, trauma, foreign body, extraluminal mass, acute laryngitis.

Pharyngeal disease clinical signs

Stertor, gagging, coughing, reverse sneezing, dysphagia; respiratory distress only in late stages.

Reverse sneezing hallmark

Inspiratory paroxysmal noise due to nasopharyngeal irritation.

Pharyngeal mass signs

Stertor, dysphagia, gagging, obstructive breathing.

DDx for pharyngeal disease

Brachycephalic airway syndrome, elongated soft palate, nasopharyngeal polyp, foreign body, neoplasia, abscess, granuloma, extraluminal mass, nasopharyngeal stenosis.

Radiography utility

Detect radiodense foreign bodies, bony changes, some masses; NOT useful for dynamic disease (paralysis, collapse).

Fluoroscopy utility

Best for dynamic disease; visualizes abnormal motion; increased radiation exposure.

Ultrasound utility

Non-invasive visualization of soft tissues and movement of larynx/pharynx.

CT/MRI utility

Detailed evaluation of masses, soft tissues, airway structure.

Scoping (laryngoscopy/pharyngoscopy)

Direct visualization of tissues + movement; be prepared for immediate airway intervention.

Normal canine larynx (inspiration)

Arytenoids + vocal folds abduct → wide symmetric opening.

Normal canine larynx (expiration)

Arytenoids + vocal folds nearly close glottis.

Laryngeal paralysis exam: equipment

Flexible laryngoscope preferred; blade laryngoscope acceptable.

Laryngeal paralysis exam: anesthesia

Short‑acting agent (propofol) to maintain light anesthesia; preserve spontaneous deep respirations.

Laryngeal paralysis exam: procedure

Assistant calls inspirations/expirations; observe arytenoid abduction on inspiration and closure on expiration.

Laryngeal paralysis exam: abnormal finding

One or both arytenoids fail to abduct during inspiration.

Dopram use in exam

IV dopram enhances arytenoid movement by increasing respiratory rate/effort.

Safety tips for laryngeal exam

Provide flow‑by oxygen; have ET tube ready; avoid exam if unable to manage post‑anesthesia respiratory complications.

Stridor vs stertor

Stridor = high‑pitched upper airway noise (larynx); stertor = low‑pitched snoring/snorting (pharynx/nasal cavity).

Common cause of stertor in dogs/cats

Elongated soft palate; brachycephalic airway syndrome; nasopharyngeal masses.