We calculate the characteristic current-voltage curve of a tunneling device based on semimagnetic semiconductor materials. The device is a heterostructure with layers of Cd1<FONT FACE=Symbol>-</FONT> x Mn x Te in which the magnetic ions Mn2+ interact strongly with the conducting electrons via the s-d exchange interaction. Thermal fluctuations of Mn2+ magnetic moments cause spin-dependent electron scattering that modifies the characteristic current-voltage curve. Our calculation shows how this electron-ion scattering is expected to affect the spin dynamics in transport measurements.