  Transport of electrons at high electric fields is investigated in an
intrinsic three-dimensional Dirac semimetal cadmium arsenide, considering the
scattering of electrons from acoustic and optical phonons. Screening and hot
phonon effect are taken in to account. Expressions for the hot electron
mobility $\mu$ and power loss $P$ are obtained as a function of electron
temperature $T_e$. The dependence of drift velocity $v_d$ on electric field $E$
and electron density $n_e$ has been studied. Hot phonon effect is found to set
in the saturation of $v_d$ at relatively low $E$ and significantly degrades its
magnitude. The drift velocity is found to saturate at a value $v_{ds} \sim
10^7$ cm/s and it is weakly dependent on $n_e$. A large saturation current
density $\sim 10^6$ A/cm$^2$ is predicted.
