You're petting your dog and your fingers catch on something that wasn't there before—a small, firm bump just under the skin. Or maybe you notice a raised area on your cat's belly while they're sprawled out in a sunbeam. Either way, the first thought is usually the same: is this something bad?
The short answer is that most lumps we see in practice are not emergencies, and many turn out to be completely benign. But "probably fine" is not the same as "definitely fine," and the only way to know for sure is to have it evaluated. Waiting and watching without a diagnosis can mean missing the window where treatment is simplest and most effective.
Are All Lumps the Same?
The range of things that can cause a lump or bump on your pet is enormous. Here are some of the most common:
- Lipomas — Soft, movable fatty tumors that sit just under the skin. Extremely common in middle-aged and older dogs. Almost always benign, though they occasionally grow large enough to interfere with movement.
- Sebaceous cysts — Blocked oil glands that form firm, round lumps in the skin. They can sometimes rupture or become infected, but they're not cancerous.
- Mast cell tumors — One of the most common skin cancers in dogs. They can look like almost anything—a small pink bump, a raised red area, or even something that resembles an insect bite. This is exactly why we don't rely on appearance alone. These must be removed promptly.
- Abscesses — Pockets of infection, often from a bite wound or foreign body. Common in cats who spend time outdoors. These are usually warm, painful, and can grow quickly.
- Histiocytomas — Small, red, button-like growths that appear suddenly in young dogs. They look alarming but are benign and typically resolve on their own within a few months.
- Soft tissue sarcomas — A group of cancerous tumors that develop in connective tissues. They tend to feel firm and attached to deeper structures, and early surgical removal with adequate margins is critical for the best outcome.
The important thing to understand is that you cannot determine what a lump is by looking at it, and neither can your vet. A lipoma can feel identical to a mast cell tumor on physical exam. The only way to know what you're dealing with is to sample the cells.
How Do Veterinarians Evaluate a Lump?
The first step is almost always a fine needle aspirate (FNA). This is a quick, minimally invasive procedure we can perform at the time of your appointment, no sedation needed. We insert a small needle into the lump, collect a sample of cells, and evaluate them under the microscope. In many cases, we can give you an answer the same day.
For masses on the surface of the skin, we may also use impression cytology—pressing a microscope slide directly against the tissue to collect cells. Both techniques give us a good initial picture of what we're dealing with.
If the aspirate results are inconclusive or suggest something that needs further characterization, the next step is a biopsy—surgically removing all or part of the mass and sending the tissue to a pathologist for a definitive diagnosis. The pathology report tells us exactly what type of tumor it is, whether it's benign or malignant, and whether the margins are clean (meaning we got it all).
When Should You Act Quickly?
While most lumps can be evaluated at your pet's next scheduled appointment, there are some signs that warrant a sooner visit:
- Rapid growth—noticeably larger over days to weeks
- Changes in color, texture, or shape
- Ulceration or bleeding from the surface
- The lump feels firmly attached to underlying tissue (not freely movable)
- Your pet is licking, scratching, or bothering the area
- Swelling that's warm or painful to the touch
If you notice any of these, don't wait for the next wellness visit. Give us a call and we'll get you in.
What Happens If a Lump Needs to Come Out?
If the aspirate or clinical behavior of a mass suggests surgical removal is appropriate, we'll discuss the plan with you in detail before scheduling anything. For many benign masses, surgery is straightforward and curative. For cancerous tumors, getting adequate surgical margins the first time around is critical—it's much harder to go back and re-excise a tumor than to take enough tissue the first time.
After removal, we almost always recommend submitting the tissue for histopathology. This gives us a definitive diagnosis and tells us whether the margins are clean. If additional treatment is needed—whether that's monitoring, follow-up imaging, or referral to an oncologist—we'll walk you through all of your options.
The Bottom Line
Finding a lump on your pet is understandably concerning, but here's the most important thing to remember: early evaluation leads to better outcomes. A lump that turns out to be benign gives you peace of mind. A lump that turns out to be something more serious is far easier to deal with when caught early and small.
If you've found something new on your pet, don't Google it and hope for the best. Give us a call at (913) 469-5869 and let us take a look. A quick aspirate can save you weeks of worrying.