title: Endoscopic scoring of mucus quantity and quality: observer and horse variance and relationship to inflammation, mucus viscoelasticity and volume.
abstract: BACKGROUND
  Endoscopic scoring of airway mucus quantity and quality has not been critically assessed.
  
  
  OBJECTIVE
  To evaluate mucus scores for 1) observer- and horse-related variance and 2) association with inflammation, mucus viscoelasticity and measured volume.
  
  
  METHODS
  Variance of scoring within and between observers and over time within horses were determined for airway mucus accumulation, apparent viscosity, localisation and colour, and correlations of mucus accumulation scores with neutrophil ratios in secretions. The relationship of accumulation score to measured volumes of 'artificial mucus' was investigated. Correlations of mucus accumulation, apparent viscosity and colour scores with measured viscoelasticity were tested. Viscoelasticity was compared between tracheal secretion samples collected ventrally and dorsally.
  
  
  RESULTS
  Mucus accumulation scoring showed excellent interobserver agreement and moderate horse-related variance, was related to measured volumes of 'artificial mucus', and correlated well with neutrophilic airway inflammation. Scores of mucus viscosity, colour and localisation showed high observer-related variance. Mucus accumulation, apparent viscosity and colour scores did not correlate with measured tracheal mucus viscoelasticity, but dorsally-localised mucus showed 2-fold higher measured viscoelasticity than ventrally-localised samples.
  
  
  CONCLUSIONS
  Mucus accumulation scores are a reproducible measure of mucus volumes in the trachea.
  
  
  CONCLUSIONS
  Endoscopic scoring of mucus accumulation is a reliable clinical and research tool. In contrast, apparent viscosity, localisation and colour scores should be interpreted with caution.
authors.affiliation: Pulmonary Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, E Lansing, USA.
authors.forename: V
authors.initials: V
authors.lastname: Gerber
authors.forename: R
authors.initials: R
authors.lastname: Straub
authors.forename: E
authors.initials: E
authors.lastname: Marti
authors.forename: J
authors.initials: J
authors.lastname: Hauptman
authors.forename: C
authors.initials: C
authors.lastname: Herholz
authors.forename: M
authors.initials: M
authors.lastname: King
authors.forename: A
authors.initials: A
authors.lastname: Imhof
authors.forename: L
authors.initials: L
authors.lastname: Tahon
authors.forename: N E
authors.initials: NE
authors.lastname: Robinson
mesh_terms: D000818:Animals; D004724:Endoscopy / Q000662:veterinary; D006734:Horse Diseases / Q000175:diagnosis / Q000473:pathology*; D006736:Horses; D007249:Inflammation / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D009093:Mucus / Q000378:metabolism / Q000502:physiology*; D015588:Observer Variation; D010858:Pigmentation; D012140:Respiratory Tract Diseases / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D014783:Viscosity