Effects of inhaled beclomethasone dipropionate on respiratory function in horses with chronic obstructive pulmonary disease (COPD)

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Abstract
The effects of beclomethasone dipropionate on pulmonary function and arterial blood gas values were investigated in horses with chronic obstructive pulmonary disease (COPD). Six mature mares, diagnosed as having COPD based on clinical signs, cytological examination of bronchoalveolar lavage and pulmonary function testing, were used. Beclomethasone dipropionate (3750 μg) was administered b.i.d. for a 2 week period with a metered dose inhaler using a mask. Pulmonary function tests and arterial blood gas analyses were performed at weekly intervals, starting before beclomethasone administration and for 4 weeks thereafter. Upper airway endoscopy and nasopharyngeal fungal cultures were performed before and after treatment. Maximal variations in transpulmonary pressure (ΔPL) were elevated in all horses at baseline. Beclomethasone administration resulted in a significant decrease in ΔPL, in 5 horses, and ΔPL, fell to within the normal range in 4 horses. Two weeks after the end of treatment, ΔPL. was at or above baseline values in all horses. Total pulmonary resistance and elastance decreased significantly during treatment and returned to or above baseline values after the administration of beclomethasone was discontinued. At baseline, PaO2 range was 53–90 mmHg. In 4 horses with pronounced laboured breathing, PaO2 increased with treatment. One horse became reluctant to inhale the beclomethasone after one week, and only a transient improvement in respiratory function was noted in this animal. One horse developed a mild lower airway infection 24 h after the beginning of treatment, but no other possible side effects were noticed. Pharyngeal fungal cultures were negative before and after treatment. It can be concluded from the results of this study that inhaled beclomethasone dipropionate causes a marked improvement of respiratory function in horses with COPD.