SERUM ALKALINE-PHOSPHATASE ISOENZYMES IN THOROUGHBRED FOALS DETERMINED BY AGAROSE-GEL ELECTROPHORESIS AND NEURAMINIDASE

In order to obtain new information on serum alkaline phosphatase isoen zymes, sera from 7, 13 and 20 month-old foals were pre-treated with ne uraminidase (sialidase of Vibrio cholerae) and electrophoresed using a commercial agarose gel system. Relative migration rate was determined for each band and compared with horse tissue extract. Non treated and pre-treated serum with neuraminidase showed 2 and 3 bands respectivel y. The most anodic band was of parenchymal liver origin and it was pre sent in all foals. The second band originated in the caecum and it was the most active. However, in 13 month-old foals, this band was not cl early determined. The 3rd one was composed of a bone origin isoenzyme (only for 7 month-old foal serum) and of caecum and liver in the older groups. The presence of the caecum isoenzyme during the horse's first year, indicates that a marked physiological caecum adaptation occurs as a consequence of a change of the diet during this period. This isoe nzyme pattern changed after a year of life, and the liver isoenzymes w ere the ones that predominated. The agarose gel electrophoretic method used, together with the pretreatment of serum with neuraminidase, app ears to be a reliable method to separate the serum ALP isoenzymes in h orse.