  We investigate the effects of an applied magnetic field on the magnetic
properties of the antiferromagnet GdCoIn$_5$. The prominent anisotropy observed
in the susceptibility below $T_N$ is rapidly suppressed by a field of just a
few Tesla. Further evidence of this low energy-scale is obtained from
magnetoresistance and magnetostriction experiments. The lattice lenght,
particulary, shows a sudden change below 2 Tesla when the magnetic field is
applied perpendicular to the crystallographic $\hat{c}$-axis. The experimental
results as a whole can be attributed to a small but non negligible higher-order
crystalline electric field.
