The damage adjacent to incisions created in dorsal mouse skin by overlapping Er3+ and CO2 laser pulses of a duration of 250 microseconds is investigated histologically. It is compared to injuries induced by long-term heating. We demonstrate how the lateral thermal damage near the laser cuts can be explained by heat conduction. We show that it is necessary to introduce as a heat reservoir a layer of tissue that has been liquified during the cutting process. The width of the thermally damaged region depends mainly on the extension of the liquid material that remains in the cut after the laser-tissue interaction.