lump on pet rats face

Question
My pet rat is almost two years old and about a week ago developed a lump under his ear. I looked at another persons question and saw your link to zymbals gland tumor. Our rat looks like the first pictures, not the last ones with the open wound/hole. The lump has pretty much been pea size(circle) and hard for the past week. Then it developed a brown spot in the center. Then tonight it appears to have popped open and has a yellow discharge that has an odor. Can you please point us in the right direction on how to help our little guy.

Answer
It may be a tumor of the zymbals gland but it can also be an abscess. Sometimes it can even be linked to the rats molars if they are infected.  I would clean it out and watch to see if it continues to fill up and or spread.  It is common for these tumors to start to eat away at the rats face and jaw etc....and if the vet is not up to par on rat care he may make it worse so be sure that your vet is aware of zymbals gland tumor should you have to take that route. I would clean the pus out and wipe it out with saline solution.  Watch it and keep me posted.