Gill loss is generally indicative of poor conditions. Axolotls who lose their gills can survive as they can breathe through their skin and gulp air, the gills will generally grow back if they are kept correctly. What would concern me was that an axolotl lost its gills in the first place. I dont wish to prejudge you standard of care , so what was the reason for the gill loss ? And how do you keep your axolotls, water peramiters, temp, cleaning schedule etc ?