title: Coughing, mucus accumulation, airway obstruction, and airway inflammation in control horses and horses affected with recurrent airway obstruction.
abstract: OBJECTIVE
  To investigate relationships between cough frequency and mucus accumulation, airway obstruction, and airway inflammation and to determine effects of dexamethasone on coughing and mucus score.
  
  
  METHODS
  13 horses with recurrent airway obstruction (RAO) and 6 control horses.
  
  
  METHODS
  6 RAO-affected and 6 control horses were stabled for 3 days. Coughing was counted for 4 hours before and on each day horses were stabled. Before and on day 3 of stabling, tracheal mucus accumulation was scored, airway obstruction was assessed via maximal change in pleural pressure (deltaPpl(max)), and airway inflammation was evaluated by use of cytologic examination of bronchoalveolar lavage fluid (BALF). Effects of dexamethasone (0.1 mg/kg, IV, q 24 h for 7 days) were determined in 12 RAO-affected horses.
  
  
  RESULTS
  To assess frequency, coughing had to be counted for 1 hour. In RAO-affected horses, stabling was associated with increases in cough frequency, mucus score, and deltaPpl(max). Control horses coughed transiently when first stabled. In RAO-affected horses, coughing was correlated with deltaPpl(max), mucus score, and airway inflammation and was a sensitive and specific indicator of deltaPpl(max) > 6 cm H2O, mucus score > 1.0, and > 100 neutrophils/microL and > 20% neutrophils in BALF Dexamethasone reduced cough frequency, mucus score, and deltaPpl(max), but BALF neutrophil count remained increased.
  
  
  CONCLUSIONS
  Because of its sporadic nature, coughing cannot be assessed accurately by counting during brief periods. In RAO-affected horses, coughing is an indicator of airway inflammation and obstruction. Corticosteroid treatment reduces cough frequency concurrently with reductions in deltaPpl(max) and mucus accumulation in RAO-affected horses.
authors.affiliation: Pulmonary Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: N Edward
authors.initials: NE
authors.lastname: Robinson
authors.forename: Cathy
authors.initials: C
authors.lastname: Berney
authors.forename: Sue
authors.initials: S
authors.lastname: Eberhart
authors.forename: Heather L
authors.initials: HL
authors.lastname: deFeijter-Rupp
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Jefcoat
authors.forename: Cornelis J
authors.initials: CJ
authors.lastname: Cornelisse
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Gerber
authors.forename: Frederik J
authors.initials: FJ
authors.lastname: Derksen
mesh_terms: D000402:Airway Obstruction / Q000150:complications* / Q000188:drug therapy / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001992:Bronchoalveolar Lavage Fluid; D003371:Cough / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D003907:Dexamethasone / Q000627:therapeutic use; D006734:Horse Diseases / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology*; D006736:Horses; D007249:Inflammation / Q000662:veterinary; D009093:Mucus / Q000502:physiology*; D012129:Respiratory Function Tests; D012137:Respiratory System / Q000473:pathology* / Q000503:physiopathology*; D013997:Time Factors
chemical_list: D000893:Anti-Inflammatory Agents; D003907:Dexamethasone