Bumps and Lumps: When Should You Worry?

You're petting your dog when suddenly your fingers stop. There's a lump. Then comes the question many pet owners immediately think: Could it be cancer?

Finding a new bump or lump can certainly be frightening, but a lump doesn’t automatically mean cancer. Pets can develop cysts, fatty masses, abscesses, enlarged lymph nodes, benign growths, and malignant tumors. Only your veterinarian can reliably determine one from the other. Even a soft, movable lump that seems innocent should not automatically be assumed to be harmless. Some tumors can look and feel very similar to benign masses.

I've had three pugs develop lumps over the years. When Lily was 17, I discovered a hard lump about the size of a dime on her neck. Within three days it had grown to the size of a quarter, and within another 24 hours I could feel that it had grown deeper as well. I moved up her veterinary appointment. A fine-needle aspiration confirmed what her veterinarian suspected: a mast cell tumor. Lily's experience taught me firsthand why a new or rapidly changing lump should never simply be watched and ignored. Pugs and Boxers are among the breeds predisposed to mast cell tumors, along with Boston Terriers and Rhodesian Ridgebacks. Lipomas are especially common in older dogs.

Not Every Lump Behaves the Same Way

One reason lumps can be confusing is that there is no single appearance or texture that tells you exactly what you're dealing with. A fatty mass may feel soft and movable, while another growth may feel firmer or more attached. An abscess may appear suddenly and can be associated with inflammation or infection. Cysts can vary considerably in appearance as well.

That's why simply looking at a lump—or even feeling it—isn't enough to identify it reliably. What matters is noticing that it is there and giving your veterinarian as much information as possible about it.

Cats develop lumps and bumps, too, as do rabbits, guinea pigs, and other pocket pets. Pet rats are notorious for developing tumors. In smaller animals, swelling around the jaw or neck can sometimes be associated with an abscess, dental problem, or enlarged lymph node rather than a tumor. Whatever species you share your home with, a new unexplained lump deserves attention.

What Should You Look For?

Start with what you can observe. Where is the lump? Does it seem to be on the surface of the skin or underneath it? Is it soft or firm? Does it move beneath your fingers or seem attached in place? Is the skin over it a normal color? Is there redness, hair loss, bleeding, discharge, or an open sore? A lump that suddenly grows, changes shape or texture, becomes painful, begins bleeding or oozing, or causes your pet to lick, scratch or chew at the area should prompt a call to your veterinarian. Location matters as well. Even a benign mass may become a problem if its size or position begins interfering with walking, eating or another normal activity. It’s especially important to know if that lump or bump is accompanied by other changes in your pet. Share as much information as possible with your vet. Your veterinarian may be able to gather useful information through an examination but your description of when you first noticed the lump and whether it has changed can be crucial in diagnosis. In many cases, a fine-needle aspirate might be recommended. A small needle is used to collect cells from the mass so they can be examined under a microscope. Some masses can be identified this way, while others may require a biopsy or additional testing.

Fine-Needle Aspiration and Biopsy Aren't the Same Thing

These terms can be confusing when you're standing in an examination room worried about your pet.

A fine-needle aspiration generally collects a small sample of cells from a mass using a needle. Those cells can then be examined to help determine what type of process may be occurring. In some cases, this provides useful diagnostic information without surgically removing the entire mass.

A biopsy is different because a piece of tissue—or sometimes the entire mass—is collected for examination. Looking at the tissue architecture can provide information that examining individual cells alone may not provide. Your veterinarian may recommend a biopsy when a fine-needle sample doesn't provide a clear answer or when more information is needed to determine what the mass is and how it should be managed.

The important point for pet owners isn't deciding which test is appropriate. It's understanding why a veterinarian may recommend additional testing even after examining a lump.

Keep Track of What You Find

If your veterinarian recommends monitoring a particular lump, don't rely entirely on memory.

Make a simple record of where it is located and the date you first noticed it. A photograph can provide a useful visual reference when the mass is visible. If your veterinarian wants you to monitor its size, ask how they would like you to do that and how often it should be checked.

With multiple lumps, a simple body diagram can also help. Numbering the masses and recording their locations can prevent confusion over which one has already been evaluated and which one may be new.

And don't assume that because one lump was previously diagnosed as harmless, the next lump will be the same thing. A new mass is a new finding.

Make the Hands-On Check a Habit

You don't need special equipment to become familiar with your pet's body. Regularly running your hands over your pet from head to tail can help you discover something hidden beneath fur that you might never see. Don't forget the legs, belly, chest, neck, and areas around the jaw.

Long or thick coats can hide surprisingly large changes. Using your hands as well as your eyes is particularly useful with pets whose skin isn't easily visible.

This doesn't need to become an anxious daily search for something wrong. It can simply become part of normal life—while petting your dog on the couch, grooming your cat, or handling a smaller pet. Over time, you become familiar with what feels normal for your animal.

That familiarity is valuable because sometimes the important discovery isn't a dramatic mass. It's simply realizing, “That wasn't there before.”

REMEMBER: The goal isn't to diagnose what you find. It's to notice when something is different.

Because moments matter.