Procalcitonin Under the Course of Budesonide Inhalation Therapy in Recurrent Airway Obstruction

• Procalcitonin (PCT) is used as a biomarker in human asthma and chronic obstructive pulmonary disease.
• We suspected PCT to be a valuable marker of treatment success in equine recurrent airway obstruction (RAO).
• Inhalative therapy (budesonide 1,500 μg BID) was performed over 10 days in 12 RAO-affected horses.
• While a significant reduction in clinical scores were found, no difference was found before and after therapy for PCT.
• Procalcitonin does not seem to be a useful marker to monitor treatment success of glucocorticoid inhalation in RAO.

Procalcitonin (PCT), a precursor protein of the hormone calcitonin, is a sensitive inflammatory marker useful in diagnosis of exacerbation of asthma and chronic obstructive pulmonary disease. In this study, PCT was evaluated as a potential biomarker for the success of budesonide inhalation therapy in equine recurrent airway obstruction (RAO). Twelve horses suffering from RAO were included in a prospective clinical study. Clinical examinations, exercise test, blood gas analysis, endoscopy, bronchoalveolar lavage fluid cytology, and thoracic radiography were performed before and after therapy and results included in a scoring system. Inhalative therapy using budesonide at a dosage of 1,500 μg twice daily was performed over 10 days. Equine-specific enzyme-linked immunosorbent assays were used to evaluate concentrations of PCT as well as interleukins-1ß and 6 in bronchoalveolar lavage fluid. A significant reduction in clinical score, in particular in dyspnea, amount, and viscosity of tracheal secretion, was found after 10 days of inhalation (P = .005). For PCT, no difference was found before and after therapy. The median PCT concentration increased insignificantly from 13.85 (6.8–42.09) ng/mL to 16.47 (2.04–151.01) ng/mL after therapy (P = .158). In conclusion, PCT does not seem to be a useful marker to monitor treatment success of glucocorticoid inhalation in RAO.