(BET Labs) Equithrox thyroid supplement is a source of L-thyroxine sodium in an apple and molasses flavored base. Use in horses for correction of conditions associated with low circulating total thyroxine (TT4) hormone. The dose of L-thyroxine sodium fed is the same per administration as that of competitors but more Equithrox will be eaten. This consistently results in higher serum concentrations of total thyroxine (TT4).