Influence of different epinephrin applications on the dimensions of the spleen in the horse

Various authors describe the positive effect of epinephrin in the treatment of nephrospienic entrapment in the horse showing colic. Epinephrin was adm inistered alone or simultaneously with a conservative treatment. After admi nistration of epinephrin the spleen contracts and, so reduced, enables the colon to regain its physiological position. Epinephrin can be administerd i ntravenously as a bolus, as an infusion or injected into the spleen. The aim of this study was to investigate the effect that administration of epinephrin has on the size of the spleen, and to note the ensuing side effe cts. Five horses were included in this study. Every second day epinephrin (Epinephrin) was administred (1) as a Bolus (4 mg/kg in 18 mi of saline), (2) intravenously as an infusion (1 mg/kg/min. d uring 5 min.) and (3) directly into the spleen (4 mg/kg in 18 mi of saline) . An ECG was mode during the entire time of each test. Blood samples were t oken at regular intervals (every 30 seconds for 5 minutes, then every minut e); blood counts were made; side-effects (perspiring, restlessness) were re corded. The size of the spleen was measured by help of sonography. Length a nd thickness of the spleen were mesured. The measurements were made before administration of epinephrin and thereafter every 5 minutes for 25 minutes. Side-effects occured with all three administrations used. The intralienal i njection of epinephrin induced a moderate tachykardie in one of the five ho rses. The epinephrin bolus induced a total heart arrythmia lasting 2 to 3 m inutes in ail horses. infusion of epinephrin caused a moderate tachycardia (72/min.). Both intravenous administrations caused the horses to perspire, Sonography enabled the quick and accurate measurement of the length of the spleen. The thickness of the spleen did not vary in a consistent way so tha t the length of the spleen was selected to evaluate its size. After intrali enal injection of after the bolus of epinephrin was injected, the spleen re duced to 68% of its original length and reached ist original length 25 minu tes later. infusion of epinephrin reduced the spleen to 52% of its original length. Using this method the contraction of the spleen lasted longer than after administering the bolus. This study demonstates that infusion of epinephrin induces a significant re duction in the length of the spleen. The side-effects with this administrat ion are moderate. Therefore, only infusion of epinephrin can be recommended for therapeutical purposes in cases of nephrosplenic entrapment.