This dog needs to be examined by a veterinarian. The salivary glands and lymph nodes are located in this area. Salivary glands in a young dog can become enlarged secondary to trauma, less commonly infection or neoplasia. Cysts are possible but not common in that area in a young dog. An abscess is possible--this is a pocket of bacteria and pus (infection) under the skin--in this area I have seen it secondary to a migrating foreign body (foxtail or grass awn). Cancer is possible but fairly unlikely because he is so young; there are also benign tumors (lipomas--fatty tumors) that can form--again his age makes this unlikely. Your veterinarian will do a fine needle aspirate; a small needle is placed in the lump to obtain some cells for review under the microscope. This will help identify the cause of the mass.
