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Efficacy of tamoxifen for the treatment of severe equine asthma

Mainguy‐Seers, Sophie, Picotte, Khristine, Lavoie, Jean‐Pierre
Journal of veterinary internal medicine 2018 v.32 no.5 pp. 1748-1753
apoptosis, asthma, dexamethasone, drug therapy, estrogen receptors, herds, horses, lung function, models, mucus, oral administration, signs and symptoms (animals and humans), tamoxifen
BACKGROUND: Tamoxifen, a selective estrogen receptor modulator, decreased airway neutrophilia and improved clinical signs in an experimental model of equine asthma, and induced neutrophilic apoptosis in vitro. HYPOTHESIS/OBJECTIVES: Tamoxifen reduces airway neutrophilia and improves lung function in severe asthmatic horses. ANIMALS: Twelve severe asthmatic horses from a research herd. METHODS: Randomized controlled blinded study design. The effects of a 12‐day oral treatment with tamoxifen (0.22 mg/kg, q24h) or dexamethasone (0.06 mg/kg, q24h) on lung function, endoscopic tracheal mucus score and bronchoalveolar lavage fluid cytology were compared. RESULTS: Tamoxifen significantly improved the pulmonary resistance (RL; mean reduction of 1.15 cm H₂O/L/s [CI: 0.29‐2.01, P = .007] on day 13), but had no effect on the other variables evaluated. Dexamethasone normalized lung function (mean reduction of RL of 2.48 cm H₂O/L/s [CI: 1.54‐3.43, P < .0001] on day 13), without affecting airway neutrophilia. CONCLUSIONS AND CLINICAL IMPORTANCE: Results of this study do not support the use of tamoxifen at the dose studied as an antineutrophilic medication in the treatment of asthmatic horses in chronic exacerbation.