Establishment of reference ranges and evaluation of in vitro concentration-dependent platelet inhibition by acetylsalicylic acid for multiple electrode impedance aggregometry in healthy dogs.

Acetylsalicylic acid (ASA, aspirin) is an antiplatelet medication used for prevention of thromboembolism. Effects of ASA appear to vary widely between dogs, but the underlying mechanisms are not understood. The Multiplate analyzer is a newer form of whole-blood impedance aggregometry recently validated for use in healthy dogs. A method utilizing this instrument to measure ASA effects on platelet function has not been established. The goals of this study were to establish reference ranges for the Multiplate in healthy dogs and secondly, to develop a technique to determine the in vitro concentration of ASA needed to cause 50% inhibition of platelet aggregation (IC50). Reference ranges established from 40 dogs at multiple test times for three agonists were consistent with previously published values. In vitro IC50 values were calculated using the sigmoid Emax model in 20 healthy dogs on two occasions to determine individual repeatability. Calculated in vitro IC50 demonstrated four ASA response groups: responder (n = 16), poor responder (n = 1), variable responder (n = 2), and nonresponder (n = 1). Multiplate within-assay variability was  <10% for area under the curve (AUC), and between-assay baseline AUC variability was  <15%. The described technique allowed for determination of an in vitro IC50 for ASA in dogs using a multiple electrode impedance aggregometer.

Evaluation of tracheal wash of horses with exercise-induced pulmonary hemorrhage treated with furosemide

Avaliaram-se os efeitos da furosemida sobre o lavado traqueal de eqüinos portadores de hemorragia pulmonar induzida pelo exercício (HPIE). Nove animais foram distribuídos em três grupos experimentais: grupo-controle, formado por três eqüinos hígidos e não portadores da doença; grupo 1, com três eqüinos portadores e não submetidos a tratamento; e grupo 2, com três eqüinos portadores da doença e tratados com furosemida na dose de 1mg/kg, quatro horas antes da atividade atlética. As amostras do lavado traqueal foram obtidas duas horas após o exercício físico e sua avaliação demonstrou que o uso do medicamento reduziu a severidade da HPIE, refletida pela redução no número relativo de hemossiderófagos (de 7,8 por cento no grupo 1 para 4,2 por cento no grupo 2) e no número de eritrócitos (de 77666 x 10³/ml no grupo 1 para 8000x10³/ml no grupo 2).