boxer with swollen bottom

Question
I have a 10 yr old boxer who of course due to his age has increasingly developed some health problems, arthritis in hips, some sort of disorder causing something similar to vertigo with head tilting several years ago and just last night I noticed that the right side of his anus was very swollen. Of course I took him to the vet this afternoon thinking it maybe his anal glands even though he NEVER drags himself, etc. She expressed them some and when she hit the right side he obviously was in a lot of pain. The vet said she felt some sort of pocket filled area but she couldn't confirm it was an abscess or tumor. She started him on antibiotics for the next 10 days and basically said we'd wait and see if that helps, if not then we'd determine what exactly it is. This really concerns me though. I know boxers are more apt to have tumors anyway. She also said his prostate is enlarged a little (he is still intact). Do you have any other ideas or suggestions to what in the world this could be with him? And at his age and declining health is it safe to have him neutered to help with the prostate enlarging? I've started him on arthritis meds that she suggested hoping I can help with his pain. He is a large part of my family and I'll do whatever I can to help him but I am concerned with waiting til his antibiotics are done to "try and figure out" what is going on with him. Please help.

Answer
While it is safe to neuter him at this age, I would wait and see what he has growing near his rectum. Dogs of this age can get peri-anal tumors and they can grow on the outside or the inside. They are not usually the kind of tumor that spreads, however they are very locally invasive and can grow very large and be very painful and bleed a lot.

The first step is to finish the antibiotics to see if they help. If they did, he could have had an abscess. The pain is also indicative of an abscess also. Tumors are rarely painful unless (and they often do) have an abscess in the tumor.

If the lump resolves and there seems to be no more pain then you have gained. But if the lump is still there, it needs to be explored further.

If he indeed has a tumor then you will have to decide what to do at that time.