Herraje y competencia como factores que alteran el equilibrio hidrosalino en equinos fina sangre de carrera

En muestras de sangre de 19 equinos FSC en plena actividad competitiva se estudio las variaciones del metabolismo hidrosalino experimentadas debido al estres siquico producido por el herraje, analizando­se ademas, en 8 de ellos, el efecto de estres fisico y siquico que constituyen la competencia mas al am­biente y manejo hipico en dias de carrera. Las variables analizadas fueron VGA, natremia, kale­mia, cloremia, osmolaridad plasmatica y potasio intraglobular. Inmediatamente despues del cambio de herradu­ras se observo un incremento significativo solo de la kalemia desde 3,5 ± 0,4 a 4,0 ± 0,3 mEq/l (p < 0,005), mientras que, una vez finalizada la carrera, se encontro un significativo incremento de la natre­mia, osmolalidad y VGA (p < 0,05), sin modifica­cion de la kalemia. El aumento postherraje de la kalemia podria ex­plicarse por el efecto que, sobre los receptores alfa de higado, musculo y globulo rojo, ejercen las catecolaminas liberadas por esa situacion de estres siquico. Los incrementos de la natremia y osmolalidad postcarrera podrian explicarse por la redistribucion acuosa debido al ejercicio, mientras que el aumento concomitante del VGA y la disminucion del potasio intraglobular estarian influenciados por el incre­mento de las catecolaminas circulantes, descrito previamente, las que actuarian sobre receptores alfa adrenergicos. Abstract The modification of the hidrosaline metabolism experimented by psychical stress produced by change of horseshoes was studied in blood samples of 19 trained thoroughbred race horses. The parameters studied were packed cell volume (PCV), erythrocytic potassium and plasmatic sodium, potassium, chloride and osmolality. In eight of these animals, the effect of physical and psychical stress implicated in competition plus race days environment and management, was also analyzed. Immediately after the change of horseshoes, a significant increment was observed in plasmatic potassium concentration from 3.5 ± 0.4 to 4.0 ± 0.3 mEg/l (p < 0.005). At the end of the race, significant increments in PCV, plasmatic sodium and plasmatic osmolality (p < 0.0001) were observed, simultaneously with a decrease in the erythrocytic potassium concentration from 94.4 ± 10.5 to 81.0 ± 5.3 mEq/l (p < 0.05), without plasmatic potassium modification. The increase in plasmatic potassium concentration determined Immediately after horseshoes change, may be due to the effect of catecholamines released by psychical stress on alfa receptors of liver, muscle and red cells. The after race increment of plasmatic sodium and osmolality may be explained by water redistribution due to exercise, while the concomitant increase of PCV and decrease of intraglobular potassium, would be mediated principally by alfa adrenergic stimulation produced by the increment of circulating catecholamines, previously communicated.