ULTRASOUND SPIROMETRY IN THE HORSE - A PRELIMINARY-REPORT ON THE METHOD AND THE EFFECTS OF XYLAZIN AND LOBELIN HYDROCHLORIDE MEDICATION

A new computerised ultrasound-based spirometry system according to Bue ss et al. (1995) modified by a double flow measurement facility was us ed to study pulmonary function in healthy horses and horses affected w ith subclinical and manifest chronic bronchiolitis (CB). The horses we re first evaluated at rest without and medication. On another occasion all horse sere tested following i.v. administration of xylazine (0.4 mg/kg) and following i.v. administration of lobelin hydrochloride (1.h y.; 0.2 mg/kg) to evaluate the effect of xylazine and 1.hy. on differe nt spirometric variables. Ultrasound-based spirometry proved to be and easily applicable method for lung function testing, even in difficult horses. However, there existed a pronounced physiological variation f or all measured lung function parameters and no significant difference s between healthy horses and horses with chronic bronchiolitis could b e found except for the expiratory tidal volume (VTE, p < 0.05). Indivi dually, a marked decrease of variability from breath to breath followi ng either xylazin and 1.hy. administration could be observed for all p arameters, except the flow-time-ratio (Tpef./Texp.) and the flow-volum e-ratio (Vpef./Vexp).