The short answer is no. Dogs, especially as they age, are prone to all sorts of benign (non-cancerous) skin growths.
Some of the most common benign lumps we see include:
- Lipomas: These are perhaps the most common lumps of all. A lipoma is just a benign fatty tumor. They usually feel soft, are movable (you can kind of “push” them around under the skin), and tend to grow very slowly. They are especially common in middle-aged to senior dogs, particularly in breeds like Labradors and Dobermans.
- Sebaceous Cysts: These are essentially large, blocked oil glands that can look like a pimple. They may rupture, ooze a white, cheesy material, and then resolve on their own, but they can also become infected.
- Warts (Papillomas): Often caused by a virus, these are common in younger dogs (especially around the mouth) or older dogs with weaker immune systems. They often look like small, cauliflower-like growths.
- Histiocytomas: These bright red, button-like, hairless lumps often appear suddenly on younger dogs (under 3 years old). The good news is they are benign and frequently go away on their own.
While all these are common, it is impossible to tell what a lump is just by looking at it.
Warning Signs: What Does a Cancer Lump on a Dog Look Like (and Feel Like)?
This is the question every owner wants answered, but it comes with a critical disclaimer:
Even the most experienced veterinarian cannot tell if a lump is cancer just by looking at or feeling it. However, certain features are considered “warning signs” that make us more suspicious and will likely prompt your vet to recommend immediate testing.
When to Seek Help—Key Warning Signs:
- Rapid Growth: This is the number one red flag. A lump that seems to double in size over a month (or even a week) is highly concerning.
- Changes in Shape or Color: A lump that was once round and is now irregular, or one that changes color (e.g., becomes red, black, or multi-colored) needs to be seen.
- Firmly Fixed: A lump that feels “stuck” to the underlying tissue or body wall (as opposed to a soft, fatty lump you can move around) is a concern.
- Ulceration or Bleeding: Any lump that breaks open, bleeds, or develops a sore that won’t heal is a major warning sign.
- Location: While cancer can appear anywhere, lumps on the mammary glands (in female dogs), around the mouth, or on the toes/nailbeds are often treated with a higher index of suspicion.
- Texture: A “cancer lump on a dog” doesn’t have one specific feel. It can be hard, nodular, and irregular. But some aggressive cancers can even feel soft, just like a benign lipoma.
The takeaway? Any change is significant. A lump that has been there for years and suddenly starts to grow or change is just as concerning as a brand-new one.
Common Types of Skin Cancer Lumps on Dogs
When a lump is cancerous (malignant), it means it has the potential to grow and potentially spread (metastasize) to other parts of the body.
A few of the more common types of skin cancer in dogs include:
- Mast Cell Tumors: These are the “great imitators” and can look like anything—from a small, innocent-looking bump to an angry, ulcerated mass. They are a very common type of skin cancer in dogs and can release histamine, causing the lump to suddenly swell or shrink.
- Melanoma: While many melanomas on haired skin are benign, those in the mouth, on the gums, or in the nailbed are often highly aggressive.
- Squamous Cell Carcinoma: This cancer is often linked to sun exposure, especially in dogs with light-colored fur and skin (like white pit bulls or boxers). They often appear on the belly, nose, or ears.
- Soft Tissue Sarcomas: This is a broad category of tumors that arise from connective tissue. They are often firm, irregular, and can be very invasive locally.
Your Action Plan: What to Do When You Find a Lump
- Don’t panic, but do act. Take a deep breath.
- Call your primary care veterinarian and schedule an appointment. Tell them you’ve found a new lump.
- What to expect at the vet: Your veterinarian will perform a full physical exam and then will likely recommend a Fine Needle Aspirate (FNA).
An FNA is the most important first step. It’s a simple, minimally invasive, and fast procedure where your vet uses a small needle to pull a few cells from the lump. They will then look at those cells under a microscope. In many cases, an FNA can immediately tell us if we’re dealing with a simple fatty tumor, a cyst, an infection, or something more serious.
If the FNA is inconclusive or suspicious for cancer, the next step is a biopsy (a small tissue sample) to get a definitive diagnosis.
Can I Prevent Skin Cancer Lumps on My Dog?
While many tumors are linked to genetics that we can’t control, there are two crucial things every owner can do.
- Routine Home Checks: The single most powerful tool for early detection is your own hands. Once a month, make a point to slowly pet your dog from nose to tail, feeling for anything new. Feel their belly, in their armpits, between their toes, and even check their gums. Get to know your dog’s normal “lumpy-bumpy” landscape so you can immediately spot a newcomer.
- Sun Protection: For dogs with thin white fur, pink noses, or exposed skin on their bellies, sun protection is key. Limit their direct sun exposure during peak hours (10 a.m. – 4 p.m.). Ask your vet about dog-safe sunscreen or UV-protectant clothing for sunbathing.
A Cancer Diagnosis is Scary, But You Are Not Alone
If your family veterinarian’s tests do confirm a cancer diagnosis, it is a scary and overwhelming moment. The most important next step is to get a clear treatment plan from a specialist.
At Metropolitan Veterinary Associates (MVA), our dedicated Oncology Specialty Department is here to provide advanced, compassionate care for your pet. Our board-certified veterinary oncologists work directly with you and your primary veterinarian to create a comprehensive treatment plan tailored to your dog’s specific needs. From advanced diagnostics and chemotherapy to immunotherapy and targeted radiation, our goal is to provide the best possible quality of life for your beloved companion.
If you have found a lump on your dog, please don’t wait. Schedule an appointment with your primary veterinarian today. And if you and your vet decide you need specialized cancer care, know that the MVA team is here to support you every step of the way.