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.