We measure the molecular loss rate by monitoring the time evolution of the average number density of trapped molecules, n (see Fig. 1 A). We fit the data to the solution of shown as solid lines in Fig. 1 A. The first term on the right hand side accounts for number loss, and we extract the measured two-molecule inelastic loss rate coefficient, β , (which is two times the collisional event rate) from the fit. The second term describes density change arising from heating of the trapped gas during the measurement. In a single measurement, we observe an increase in temperature that is at most 50%. In subsequent analysis, we fit the measured temperature to a linear heating and obtain a constant slope c . In Eqn. 1, we then use α = 3 2 c T + $_{ct}$, where T is the initial temperature of the gas (see also [21]). Fig. 1 B shows a summary of our experimental data, where we plot β/T , as a function of d . We plot the ratio β/T because the Wigner threshold law for p -wave scattering predicts that β scales linearly with T , and we previously verified this temperature dependence at d = 0 Debye [21]. For the data in Fig. 1, T ranged from 250 nK to 500 nK. In Fig. 1 B we see that dipolar interactions have a dramatic effect on the inelastic collision rate. At low electric field, where d is below 0.1 Debye, we observe no significant modification to the zero electric-field loss rate (which is plotted at d = 0 . 01 Debye for inclusion on the logarithmic scale). However, for higher electric fields, we observe a rapidly increasing loss rate, with well over an order of magnitude increase in β/T by d = 0 . 2 Debye. Fitting the data for d > 0 . 1 Debye, we find that the inelastic rate coefficient follows a power-law dependence on d , β/T ∝ d $^{p}$, where p = 6 . 1 ± 0 . 8. To understand this strong electric-field dependence of the inelastic loss rate, we consider a relatively simple quantum tunneling model where the loss is assumed to be due to collisions between fermionic molecules that proceed via tunneling through a p -wave centrifugal barrier followed by unit probability for loss at short-range [14]. The fact that we do not observe any resonant oscillations as a function of E-field (see Fig. 1 B) is consistent with a very high loss probability for molecules reaching short range. In an applied electric field, the long- range dipole-dipole interaction ∝ 1 R 3 , where R is the intermolecular separation, significantly modifies the height of the p -wave barrier, and thus changes the inelastic collision rate. Moreover, the fact that the dipole-dipole interaction is spatially anisotropic means that 5 dn dt = − βn 2 − αn, (1)