Orthorhombic perovskites provide a perfect playground for investigations of novel magnetic phenomena, such as ferroelectricity, ultrafast spin reorientation, colossal magnetoresistance, and many others. Here, the authors combined magnetization and neutron scattering measurements with crystalline electrical field calculations to characterize the magnetic properties of a DyScO single crystal. They establish that Dy moments have a strong Ising-like single-ion anisotropy with a doublet ground state and an enormous value of effective moment. This results in a significant dipolar interaction, which strongly suppresses conventional transverse fluctuations and makes magnetic excitations invisible to neutron spectroscopy.