Pharyngeal Collapse in Dogs: Fluoroscopy Links Severity to Age and Brachycephaly

Fluoroscopic Assessment of Pharyngeal Collapse in Dogs and Its Association With Age, Breed, and Tracheal and Bronchial Collapse

Soowan Kim, Minjoo Kwon, Hye-yeon Choi, Jihye Choi, Junghee Yoon

Background:
Pharyngeal collapse (PC) is a dynamic upper airway disorder increasingly recognized in dogs, particularly those with brachycephalic conformation. While its coexistence with other airway collapses—such as tracheal collapse (TC) and bronchial collapse (BC)—has been noted, the clinical significance and interrelationships between PC severity, clinical signs, and airway pathology remain poorly defined. This study aimed to investigate associations between PC severity and patient age, breed, and concurrent airway abnormalities using fluoroscopy.

Methods:
This retrospective study evaluated fluoroscopic examinations of 95 client-owned dogs assessed between April and September 2024 for respiratory signs or prior to anesthesia. Pharyngeal and tracheobronchial collapses were graded by three blinded observers. Clinical data including age, breed, body condition score, and respiratory signs (e.g., cough, upper respiratory sounds, cyanosis/respiratory distress) were extracted. Statistical correlations were assessed using Pearson's correlation coefficient, and interobserver reliability was evaluated using intraclass correlation coefficients (ICCs).

Results:
Pharyngeal collapse was identified in 38.9% of dogs, with Grade 2 (complete collapse) observed in 7.4%. PC severity showed significant positive correlation with age (r = 0.30), brachycephalic conformation (r = 0.46), and presence of cyanosis or respiratory distress (r = 0.26), all p < 0.05. However, no significant correlation was found between PC severity and TC or BC. Tracheal collapse and BC were present in 70.2% and 67.6% of PC cases, respectively, but their severities did not correlate with PC grade. Interobserver agreement for PC and TC grading was excellent (ICC > 0.87).

Limitations:
The retrospective design limited standardization of clinical data and imaging quality. Comorbidities (e.g., heart disease, rhinitis) and use of sedatives in some dogs may have confounded findings. The small number of dogs with Grade 2 PC (n = 7) restricts definitive conclusions about the most severe presentations. Furthermore, the study was conducted at a tertiary referral center, which may limit generalizability to the broader canine population.

Conclusions:
Pharyngeal collapse is associated with age, brachycephalic skull conformation, and respiratory distress in dogs. Fluoroscopy is a valuable diagnostic tool for assessing PC severity, particularly in brachycephalic and older dogs. Although PC often coexists with tracheal and bronchial collapse, these conditions may progress independently. Comprehensive fluoroscopic assessment should be considered in dogs with upper airway signs to inform diagnosis and guide management strategies.

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