Dog health question

Question
I have a 1 year old male Doberman. About 2 weeks ago we discovered that he has 3 quarter size lumps under his skin on the top side of his neck. I am taking him to his vet Monday for a look at.  But I was wondering what the possible causes might be?

Answer
There are many things that can cause these lumps.  The most obvious one is after a vaccination because that's where vaccines are given.  There could be bug bites, a bacterial skin infection, sebaceous cysts, or even tumors, although they would be rare in a young dog.