Endoscopes

Endoscopic Assessment of Airway Inflammation in Horses

K. Koblinger, J. Nicol, K. McDonald, A. Wasko, N. Logie, M. Weiss, and R. Léguillette

ABSTRACT

Background: Comprehensive endoscopic scoring of the upper and lower airways for in?ammation has not been critically assessed among a large population of horses. The relationship between upper and lower airways described in humans by the “one airway, one disease” concept might also apply to horses.

Hypothesis/Objectives: To evaluate if an association exists between endoscopic in?ammatory scores and mucus scores of upper and lower airways and to investigate if endoscopic ?ndings correlate with the lower airway in?ammation measured by bronchoalveolar lavage (BAL) cytology.

Methods: Prospective ?eld study. Pharyngitis, pharyngeal mucus, tracheal mucus, tracheal septum thickness, and bronchial mucus were scored using new and previously described scoring systems on a convenience sample of 128 horses with and without lung in?ammation. Based on BAL ?uid cytology, horses were categorized as having normal, moderate, or severe in?ammation of the lower airways.

Results: All 5 endoscopy scores showed excellent interobserver agreement. Tracheal mucus (P < .001), tracheal septum thickness (P = .036), and bronchial mucus (P = .037) were signi?cantly increased in horses with severe in?ammation BALs and were correlated among themselves but not with upper airways scores. BAL neutrophils percentage was correlated with tracheal mucus (rs = 0.41, P < .001), bronchial mucus (rs = 0.27, P = .003), and had a weak negative correlation with pharyngitis (rs = 0.25, P = .004).

Conclusions and Clinical Importance: Lower airway endoscopy scores are re?ective of lower airway in?ammation; however, upper and lower airways are independent in terms of severity of in?ammation. Therefore, observing upper airway in?ammation is not an indication to test for lower airway in?ammation.

Scoring sheet for mucus and inflammation in the upper and lower airways:

(Click here for a printable PDF version)

Upper airway:

Pharyngitis  - (Raker 1978)

Grade I: few small lymphoid follicles dorsal pharynx
Grade II: many small lympoid follicles dorsal and lateral pharyngeal walls
Grade III: Many close pink and white follicles dorsal and lateral extending below guttural pouch openings and to soft palate
Grade IV: same area covered but large edematous follicles

Pharyngeal mucus accumulation

Score 0: no mucus at all
Score 1: little blobs of mucus ventrally and abaxially to the epiglottis
Score 2: Confluent or large amounts of mucus ventrally as well as dorsally to the epiglottis, occasionally mucus accumulating in the ventricle sand corniculate processes

Lower airway

Trachea mucus accumulation (validated in other studies)

Score 0: none (clean singular)
Score 1: little (multiple small blobs)
Score 2: moderate (larger blobs)
Score 3: marked (confluent, stream-forming)
Score 4: large (pool-forming)
Score 5: extreme (profuse amounts)

Tracheal septum thickness

Score 0-4 (figure one)

Bronchial mucus accumulation – adapted the tracheal mucus scoring system to the bronchi (scored using the videoendoscope being advanced from the tracheal septum into the left lung until wedged)