Question:
Many of the fawns I am currently seeing here in Santa Barbara County appear to have growths or swelling on their necks or chin about the size of a baseball. I've seen this over the last several years. What's up?

Answer:
According to DFG Veterinarian Dr. Ben Gonzales, deer can have multiple lumps due to cutaneous tumors (aka papillomatosis or fibromas) which are thought to be induced by viruses.

The location you describe of these lumps makes him think they are more likely jaw abscesses which can develop from a broken tooth, or more likely from the migration of grass awns or foxtails. Foxtails migrate forward and find the path of least resistance. The body tries to fight this foreign body by delivering white cells (neutrophils), which collect, die and form pus-filled abscesses. The abscesses also find the path of least resistance between tissue layers and thus can end up on the upper neck. Since this is the time of year when foxtails are dry and are easily picked up and ingested during feeding, my best educated guess is that you're seeing foxtail-induced abscesses.