My name is***** and I can help you and Shawn this evening. Older dogs can have lumps for many reasons and most are benign but some can be more serious.
Lumps can be tumors such as lipomas (benign fatty tumor), mast cell tumors (malignant immune tumors), sebaceous adenomas (benign oil gland tumors that look like warts), and others.
Lumps can also be things like an abscess, foreign material under the skin, hives and others.
The best bet is to have your regular veterinarian examine the lump. They will look at it and determine if a fine needle aspirate is indicated (putting a needle in the lump, removing some cells and looking at them under the microscope). Once the exact diagnosis is made, they will recommend a treatment plan.
Best regards, ***** ***** this answer helps you.
Feel free to contact me if you have any more questions.
Kansas State University,
College of Veterinary Medicine Class of 2001