:S, it sould be wither a tumor or a growth, get it cheked out by your local vet, my cat had the same problem, she had 2 lumps on her neck we had them amputated but more began to grow back and one stated to form on her lungs which increased her breathing, I'm telling you, don't leave it !! Your dog WILL suffer, I'm sure she/he is in some form of discomfort so please for your dogs sake take him/her to the vet
