Serum glycosaminoglycan (GAG) composition was studied in horses. Compa
rison was made between GAG mixtures obtained from four trained horses
and four untrained horses, and with plasma GAGs from two trained horse
s. Moreover, the concentrations and characteristics of serum GAGs were
evaluated in four trained horses al different times after a show jump
ing competition. GAGs were isolated, fractionated and analysed by anio
n exchange chromatography. GAG concentrations, expressed in terms of a
minosugars, were significantly (p<0.025) higher in serum from trained
horses than in serum from untrained horses.Analytical data suggest sim
ilar serum GAG composition in trained and untrained horses. Chondroiti
n sulphate, measured in terms of galactosamine, and keratan sulphate,
measured in terms of galactose, were the main components, and observed
in the ratio 4 to 1. About 50% of the GAG chains were undersulphated.
Following competition, a decrease of serum GAG concentrations was con
stantly observed.