SCINTIGRAPHICAL EVALUATION OF ALVEOLAR CLEARANCE IN HORSES

This study proposed a standardized method for measuring alveolar epith elium membrane permeability in the horse. The normal rate of clearance (%.min(-1)) from lung into blood of nebulized Tc-99m-DTPA has been es tablished for healthy horses (Group A) compared with values obtained w ith horses suffering from chronic obstructive pulmonary disease (COPD; Group B). The Tc-99m-DTPA clearance was measured in the caudoventral (R-1) and in the half caudal (R-2) parts of the left lung during diffe rent time intervals. The two regions aimed to define the influence of the airways on measured clearance (R-2 contained proportionally more c onducting airways than R-1). It was concluded that a comparison of gro ups of subjects may be performed in R-2 and on data collected during a 20 min period. The normal clearance rate in R-2 was 1.80+/-0.46%.min( -1) (T-1/2R2=40.99+/-12.45 min) in Group A. In Group B, a significantl y faster Tc-99m-DTPA transfer rate was found (4.17+/-0.83%.min(-1) or T-1/2R2=17.17+/-3.38 min). Bronchoalveolar lavage (BAL) suggested that the increased permeability measured in Group B could be the result of lung inflammatory responses. Our results have demonstrated the abilit y of the Tc-99m-DTPA clearance test to detect alveolar epithelial dama ge in horses. Furthermore, we were able to show that a regional analys is of the alveolar-capillary barrier integrity may be performed satisf actorily in the equine patient.