By:  Dr. Callowaydr calloway

I noticed this lump on my pet.  Do I need to be worried about it?”  I get asked this question by animal owners several times a day, about all sorts of lumps and bumps in all sorts of places.  My answer is usually, “well, maybe”. 

I know it’s not a very specific answer, but it’s the truth!  The good news is that a lot of the lumps and bumps you can feel on your dogs skin are benign.  The bad news is that there are some that are malignant (cancerous).  It’s absolutely impossible to tell by look and feeling it which of the two categories it falls into.  In order to know if you need to worry about it, we need to do testing.

One type of testing we can do is called a fine needle aspirate.  Basically, it involves poking the lump with a needle to collect some of the cells.  We put these cells onto a slide, and then send the slide to the lab.  A specially trained veterinarian, called a pathologist, will look at the cells underneath a microscope and give their opinion as to whether or not the lump is malignant.  This is a great starting point and the least expensive option – if the pathologist can give you an answer.  Unfortunately, the pathologist cannot always give you an answer – sometimes the lump is so solid that we can collect enough cells, or collecting the cells is too bloody and the pathologist can’t differentiate between the cells in the blood and the cells from the lump.

Another type of testing we do is called a biopsy.  This is the “gold standard” and the ONLY way to get a certain, definitive answer as to whether or not the lump is cancerous.   This requires your veterinarian to surgically remove the lump, or sometimes sample a piece of it.  The entire lump is sent to the lab and the pathologist can then look in more detail at what kind of tissue the lump is made up of.  This is more expensive than the fine needle aspirate because usually full anesthesia is required, and the lab usually charges more for this service.  However, it usually possible to entirely remove the lump during this procedure, which may be the only treatment needed if it turns out that the lump is cancerous! 

I wish I had a crystal ball or x-ray goggles so that I could tell you what kind of lump it is by looking at it.  But until those have been invented, we have to actually send the lump to a pathologist to see what it is!