Good luck with the vet visit. Ginger, my 11 year old Golden has a number of benign fatty tumors on her chest/abdomen... We get each one checked out but they are all benign. They are very common in older dogs and in Golden especially. If the lump is just under the skin and is moveable rather than attached to the underlying tissue, it's most likely to be a fatty tumor according to my vet. We also get needle aspirates done to doublecheck.