QUANTIFICATION OF ANTIGEN-SPECIFIC ANTIBODY CONCENTRATIONS IN TRACHEAL LAVAGE FLUID OF HORSES WITH SUMMER PASTURE-ASSOCIATED OBSTRUCTIVE PULMONARY-DISEASE

Objective-To determine whether horses with summer pasture-associated o bstructive pulmonary disease (SPAOPD) have increased concentrations of antigen-specific IgG and IgE in tracheal lavage fluid, compared with values in clinically normal horses. Animals-8 horses (6 females, 2 gel dings; 6 Quarter Horses, 2 Appaloosas), 14 to 23 years old and with pr evious diagnosis of SPAOPD, served as the principal group; 8 horses (2 females, 6 geldings; 1 Quarter Horse, 7 Thoroughbreds), 6 to 9 years old, with no evidence of respiratory tract disease, served as the cont rol group. Procedure-Data were collected twice during a 1-year period: when all SPAOPD-affected horses were manifesting clinical signs of di sease (July), and when all SPAOPD-affected horses appeared clinically normal (February). On each occasion, clinical evaluations were perform ed and blood and tracheal ravage fluid samples were collected. Transtr acheal lavage supernatant was evaluated for mold antigen-specific IgG and IgE concentrations. Results-Median IgE relative antibody unit (RAU ) values were significantly higher in control, compared with principal , horses. The SPAOPD-affected horses had increased concentrations of s pecific IgG for only 1 antigen, during winter sample collection. Concl usion-Antigen-specific IgG and IgE RAU values were not increased in SP AOPD-affected horses when these horses were manifesting clinical signs of disease.