My 8yr old Boston has a disappearing lump on his right side.

[krrslater]

He has had it for about 4 years now. It comes and goes, is soft and doesn't hurt him when its there. Everytime I get him to the vet it seems to be too small to biopsy. What could this be?

[ginger899]

I honestly don't know. It sounds like it may be fluid, or possibly a cyst. Cysts can drain and then fill up again. They are 'encapsulated' so have a membrane inside which the fluid collects. Sometimes if they spontaneously drain, because the membrane is still there, they can collect fluid again.
Now that's just a guess, and I may be wrong. No-one should assume any lump or swelling is harmless, because every one needs to be tested to be sure.

Another thought is -could it be a hernia of some kind? Again that's just a wild guess.

[krrslater]

Thank you. I will keep you posted. Going to the vet Monday. Had problems breathing last night and showed some pain to the lump