Objectives: To determine the effects of pentoxifylline (PTX) administration on lung function and results of cytologic examination of bronchoalveolar lavage fluid in horses affected by recurrent airway obstruction (RAO).
Animals: 10 RAO-affected horses.
Procedures: 6 horses were orally administered PTX (16 g) mixed with corn syrup, and 4 horses were administered corn syrup alone, twice daily for 14 days. Pulmonary function was evaluated before administration (day 0) and on days 8 and 15. Bronchoalveolar lavage (BAL) was performed on days 0 and 15. Reversibility of airway obstruction was assessed by measuring pulmonary function before and after administration of atropine (0.02 mg/kg, IV). Serum concentration of PTX was measured in 4 horses 30 minutes and 2 and 4 hours after administration of PTX on days 1, 2, 3, 7 and 14.
Results: Administration of PTX to BAO-affected horses resulted in a decrease in elastance value on day 8 and on elastance and resistance (RL) values on days 8 and 15. Results for cytologic examination of BAL fluid obtained on day 15 did not differ significantly, compared with values for day 0. Values of RL decreased in all horses following administration of atropine. When mixed in corn syrup and administered orally, PTX was poorly absorbed in horses, and there was noticeable variation in serum PTX concentrations over time and among horses.
Conclusions and clinical relevance: Based on these results, it can be concluded that administration of PTX at high doses improved respiratory function of RAO-affected horses maintained in an unfavorable environment.