The lump on the neck of your dog can be lipoma (a fatty tumor), a cyst, sebaceous cyst or sweat cyst. It can also be the side effect of vaccine. I advise you to visit veterinary doctor for differential diagnosis and its proper treatment.

 Lizgroover,

 

Lymph nodes and salivary glands are found in the neck—it is
possible these are enlarged and are what you are feeling.  Lymph nodes can be enlarged due to
inflammation, infection, or lymphoma ie cancer.  Lymphoma affects dogs of all ages and needs to
be ruled out.  Salivary glands can become
enlarged due to trauma, infection, or neoplasia.  It could also be a mass arising form the skin
or subcutaneous tissue —masses can be benign like a cyst or lipoma or malignant
like a tumor.  A fine needle aspirate and
cytology needs to be done by your veterinarian for a diagnosis and treatment
plan.

 

Ann Falk, DVM

 It is possible that it is cancer. My dog had the same thing and I took her to the vet and found out it is cancer, I went and had it removed and then a year later she got many more of them and it is in different spots.