Which clinical finding is most informative for diagnosing feline upper airway disease?

• A. Stridor or stertor and abnormal inspiratory effort on physical examination
• B. Fever without respiratory signs
• C. Normal inspiratory effort
• D. Lameness

Answer: (A)

The key thing this question tests is recognizing signs that indicate obstruction in the upper airway. When the extrathoracic airway is narrowed or dynamic, you’ll often hear abnormal sounds and see increased work of breathing during inspiration. Stridor or stertor are classic audible clues: stridor is a high-pitched, harsh sound from turbulent flow in a narrow larynx or trachea, while stertor is a snoring-like noise from obstruction in the pharynx or nasal passages. When these noises accompany abnormal inspiratory effort on physical examination, they strongly point to an upper airway problem rather than a lower airway or systemic issue.

Fever without respiratory signs doesn’t specifically indicate upper airway disease, and normal inspiratory effort argues against significant airway obstruction. Lameness is unrelated to the airway. So the combination of inspiratory noises (stridor or stertor) with abnormal inspiratory effort best identifies feline upper airway disease.