By performing a series of thermodynamic measurements in an applied magnetic field $H_{textrm{ext}}$, we investigated the effects of Eu substitution on the Pr sites in filled skutterudite compound Pr$_{1-x}$Eu$_x$Pt$_4$Ge$_{12}$ ($ 0 leq x leq 1$). A heat capacity Schottky anomaly is present over the whole doping range. For the samples with $x > 0.5$, these Schottky anomaly peaks shift to lower temperature with increasing $H_{textrm{ext}}$. We argue that this behavior reflects the antiferromagnetic (AFM) ordering of the Eu moments, as the AFM transition is suppressed by $H_{textrm{ext}}$. The Schottky peaks in the samples with $x leq 0.5$ shift to higher temperatures with increasing magnetic field, signaling the presence of an internal magnetic field due to short-range AFM correlations induced by magnetic moments of neighboring Eu sites. In low $H_{textrm{ext}}$, the Schottky gaps show a non-linear relationship with $H_{textrm{ext}}$ as the magnetic moments become weakly magnetized. In high $H_{textrm{ext}}$, the magnetic moments of Eu sites become completely aligned with $H_{textrm{ext}}$. Thus, increasing $H_{textrm{ext}}$ does not further increase the magnetization, hence the Schottky gaps increase linearly with $H_{textrm{ext}}$
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