Efficacy Of A Plant Based Formulation In The Treatment Of Recurrent Airway Obstruction In Horses

The purpose of this double blinded placebo controlled cross-over clinical study was to assess the ability of a plant based formulation (Ginkgo biloba L., Zingiber officinale Roxburgh, Chlorella pyrenosa) to prevent or delay the onset, decrease the magnitude of response and/or speed the recovery of lung dysfunction, clinical signs of disease, airway inflammation, and pulmonary oxidative stress in horses with recurrent airway obstruction (RAO) on exposure to organic dust. The performance of the active supplement was judged on the basis of responses in lung function, clinical examination, airway inflammation and pulmonary oxidative stress following organic dust challenge compared to responses on the placebo diet. Lung dysfunction was assessed by measuring airway reactance and airway responsiveness to histamine by forced oscillation mechanics. Clinical signs were assessed by assigning scores for respiratory rate, nasal discharge, abdominal lift/expiratory effort, nasal flaring, lung sounds and cough. Airway inflammation was determined by cytological analyses of tracheal wash and bronchoalveolar lavage fluid (BALF) samples, and by measuring the concentration of hydrogen peroxide in exhaled breath condensate (EBC). Oxidative stress was assessed by measuring the concentrations of reduced ascorbic acid, dehydroascorbate (DHA, oxidised ascorbic acid), reduced glutathione and oxidised glutathione in tracheal wash and BALF. Results of statistical analyses demonstrated that BALF ascorbic acid concentrations were higher after challenge in horses when fed the active formulation compared to the placebo and that BALF, DHA and ARR (ratio of DHA to total ascorbic acid), were lower after challenge in the active supplement horses irrespective of the order of treatment allocation.

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