When to Worry About Lumps and Bumps on Your Dog‘s Skin: A Vet‘s Perspective
As a veterinarian and lifelong dog lover, I know firsthand how concerning it can be to discover a new lump or bump on your beloved canine companion. That sinking feeling in the pit of your stomach, the worry that races through your mind – I‘ve experienced it myself with my own dogs and guided countless clients through it as well.
The good news is that the vast majority of skin lumps in dogs are benign, posing no serious health risk. However, a minority can represent malignant cancerous tumors that require prompt treatment for the best prognosis. By educating yourself on the types of growths dogs commonly develop and what warning signs to look out for, you can be a proactive partner in keeping your pup healthy.
How Common Are Skin Lumps in Dogs?
Skin lumps and bumps are among the most common health issues seen in dogs, especially as they enter their senior years. Older dogs (>7 years) have a 40-50% chance of developing at least one skin lump within a given year, based on data from veterinary insurance agencies.
Across all ages, it‘s estimated that skin and subcutaneous tissue masses comprise 20-40% of all canine tumors. Thankfully, more than half of these growths prove to be benign. Sebaceous cysts, lipomas, and skin tags are some of the most frequently diagnosed benign lumps.
Types of Skin Lumps and Bumps on Dogs
Dogs can develop countless different kinds of lumps, bumps and masses on or under their skin. These skin lesions may be benign or malignant tumors, cysts, infections, allergic reactions, or other inflammatory conditions. Here is a breakdown of common bump types with their relative prevalence:
| Type | Description | % of Skin Masses |
|---|---|---|
| Lipoma | Soft, moveable benign fatty tumors | 25% |
| Sebaceous cyst | Small, firm, whitish bumps from clogged oil glands | 15% |
| Skin tag | Fleshy, fibrous benign growths, often in skin folds | 10% |
| Mast cell tumor | Potentially malignant tumors, can look like innocent bumps | 10-15% |
| Melanoma | Dark-pigmented benign or malignant tumors | 5% |
| Histiocytoma | Benign, button-like masses common in young dogs | 5% |
| Squamous cell carcinoma | Malignant tumors often on exposed, light skin | 3-5% |
| Basal cell tumor | Slow-growing, benign tumors in middle-aged/older dogs | 3-5% |
| Wart | Viral papillomas, often in puppies/young dogs | 3% |
Data from [@Villalobos2018; @Dobson2002; @Hauck2012; @Withrow2020]
Note that this is not an exhaustive list and definitive diagnosis requires veterinary testing. But this provides an overview of the types of bumps most commonly seen on dogs‘ skin.
When to Be Concerned About a Skin Lump
As a general rule, have your veterinarian check any new lump or bump you find on your dog as soon as possible. This is especially important for fast-growing, changing, irritated, or otherwise abnormal looking masses.
Malignant skin tumors like mast cell tumors, melanomas, lymphomas, squamous cell carcinomas and others are of greatest concern, as they can grow quickly, cause pain, and spread internally. Owners should be on alert for these warning signs that a bump may be cancerous:
- Rapid increase in size
- Redness, swelling, heat or discharge
- Ulcerations or bleeding
- Irregular, poorly defined edges
- Firm attachment to skin or underlying tissues
- Changes in color or texture
- Lymph node enlargement near the mass
If you notice any of these red flags with your dog‘s lump, schedule a vet visit immediately. Early diagnosis and treatment are critical for malignant tumors and can make a significant difference in your dog‘s outcome and quality of life.
Diagnostic Process for Canine Skin Lumps
When you bring your dog to the vet for a new lump, they will start with a thorough history and physical exam. Key information to share includes:
- When you first noticed the lump
- Any changes in size, shape, color, etc.
- If it seems painful or bothers your dog
- Any other symptoms like lethargy or decreased appetite
Your vet will carefully palpate the lump, assessing its size, consistency, mobility, and location. They will also check for any nearby enlarged lymph nodes or other abnormalities.
In most cases, the next diagnostic step is a fine needle aspiration (FNA). This quick, minimally invasive procedure involves inserting a thin needle into the mass and extracting cells to examine under a microscope. FNA can diagnose many common skin lumps like lipomas and sebaceous cysts.
However, some masses yield inconclusive results on FNA due to low cell yield, excessive blood contamination, or poor cell preservation. Certain tumor types like mast cell tumors and soft tissue sarcomas may require a biopsy for definitive diagnosis.
An incisional biopsy involves surgically removing just a small portion of the mass, while an excisional biopsy removes the entire lump. The tissue is then processed and analyzed by a veterinary pathologist. Biopsy is the gold standard for diagnosing skin tumors, grading malignancies, and guiding treatment decisions.
Your vet may also recommend staging tests to check for metastasis (spread) if a malignant tumor is diagnosed or suspected based on exam and aspirate. Staging often includes lymph node aspirates, abdominal ultrasound, and chest x-rays.
Treatment Options for Skin Lumps in Dogs
Treatment recommendations depend on the specific diagnosis, location of the mass, and overall health of the dog. Here are some common therapeutic approaches:
-
Monitoring: Small, benign lumps like sebaceous cysts and skin tags often don‘t require any treatment if they are not irritating the dog. Your vet will recommend rechecking periodically to ensure no changes develop.
-
Surgical removal: Surgery is the treatment of choice for most skin lumps, both benign and malignant. For malignant tumors, obtaining clean margins (no cancer cells seen microscopically at the edge of the excised tissue) is key to preventing local regrowth. Some benign masses may also be removed if they are large, irritating, prone to recurrent infections, or interfering with your dog‘s normal activities.
-
Chemotherapy: Certain malignant tumors have a high risk of spreading internally, even if the primary mass is completely excised. Chemotherapy drugs may be recommended following surgery for tumors like high grade mast cell tumors, melanomas, and soft tissue sarcomas. Chemo protocols vary, but often involve a combination of injectable and/or oral medications given over 12-24 weeks.
-
Radiation: Radiation therapy uses high energy x-rays targeted to a localized area to damage and kill cancer cells. It may be used as the sole treatment for inoperable tumors, following incomplete surgical removal, or to address metastasis. Radiation is commonly utilized for localized mast cell tumors, oral melanomas, soft tissue sarcomas, and other locally aggressive cancers.
-
Immunotherapy: Newer immunotherapy treatments harness the dog‘s own immune system to fight cancer. The canine melanoma vaccine is one such option, approved for the treatment of oral melanomas following surgery and/or radiation. It works by stimulating an immune response against the tumor cells to prevent or slow down progression.
-
Multimodal therapy: Many dogs with malignant skin tumors benefit from a combination of surgery, chemo, radiation and/or immunotherapy. This multi-pronged approach targets cancer cells in different ways for the greatest chance at long-term control or cure.
Your vet will discuss all appropriate treatment options based on your dog‘s specific case. Factors that influence recommendations include the mitotic index (measure of cell division) of malignant tumors, evidence of spread to lymph nodes or other organs, location and size of the mass(es), previous treatment responses, potential side effects, and overall quality of life.
Case Study: Mast Cell Tumor Treatment Success
To illustrate how proper diagnosis and prompt treatment can lead to positive outcomes even with malignant skin tumors, consider the case of Bella, an 8 year old Boxer who presented to our clinic for a small, pink raised mass on her left shoulder.
Boxers are predisposed to mast cell tumors, so this was at the top of our differential list. An aspirate and biopsy confirmed a grade II mast cell tumor. Thankfully, staging showed no evidence of spread and we were able to remove the mass with wide clean margins on the first surgery.
Bella recovered well from surgery and went on to complete a 12-week course of oral chemotherapy. Rechecks over the next 2 years showed no regrowth or new masses. At 12 years old now, Bella remains happy, active and cancer-free. Her case highlights how successful treatment absolutely is possible for many dogs with skin tumors.
Photos shared with owner‘s permission.
How to Prevent Skin Lumps and Bumps on Your Dog
While we can‘t entirely prevent every skin lump and bump from developing on our dogs, there are key steps owners can take to reduce risk factors and catch growths early:
-
Perform regular at-home lump checks. Make it a habit to run your hands over your dog‘s entire body once a month, noting any new or changing lumps. Pay special attention to "hidden" areas like the underside, groin, armpits, and inside the mouth.
-
Schedule regular vet visits. Routine exams allow your vet to find lumps when they are tiny as well as monitor any existing growths for changes. Aim for annual wellness visits at minimum; twice yearly is ideal for seniors.
-
Keep high-risk areas protected from sun. For light coated dogs and those with pink/white skin, minimize midday sun exposure and use pet-safe sunscreens on ear tips, nose, and other exposed areas.
-
Manage allergies and skin infections. Chronic allergic skin disease and recurrent infections may increase the risk of certain tumors. Work with your vet to get any skin issues well controlled.
-
Feed a balanced diet and maintain healthy weight. Proper nutrition supports skin and immune health. Obesity is a risk factor for skin fold infections, orthopedic issues, and some tumors.
-
Consider routine fine needle aspirates. For high-risk breeds like Boxers, Weimaraners and Boston Terriers, some vets recommend proactive aspirates of any lumps to catch potential mast cell tumors early. Discuss this with your vet based on your dog‘s unique profile.
While we all hope to never find a suspicious lump on our dogs, being proactive truly can make a difference. In fact, research shows that skin tumors diagnosed at < 3 cm carry an exponentially better prognosis than larger masses [@Smedley2011; @Kiupel2011].
When a Lump Isn‘t Just a Lump
Finding an unexplained lump or bump on your dog can be a heart-stopping moment for any owner who loves their canine companion fiercely. That flash of fear, that gnawing uncertainty rising in your gut – I‘ve been in those shoes myself.
But here‘s what I‘ve learned both personally with my own dogs and in my years of veterinary practice: Knowledge is empowering. By familiarizing yourself with the types of lumps dogs commonly get, what warning signs to look out for, and what testing and treatment options exist, you are already several steps ahead of any bumps that may come your pup‘s way.
Armed with this knowledge and by partnering with your trusted veterinarian, you can face any lumps and bumps with a clearer understanding and a proactive plan. Because at the end of the day, there is no one who knows your dog better than you. Trust your instincts, advocate for your canine friend, and know that excellent care and positive outcomes absolutely are possible.
Together, you and your vet can help keep your loyal companion living their happiest, healthiest, lump-free life by your side for many years to come. And that is something we can all strive for.
References
- Dobson, J., Samuel, S., Milstein, H., Rogers, K., and Wood, J. 2002. Canine neoplasia in the UK: Estimates of incidence rates from a population of insured dogs. Journal of Small Animal Practice. https://doi.org/10.1111/j.1748-5827.2002.tb00066.x
- Hauck, M. 2012. Tumors of the skin and subcutaneous tissues. In: Withrow and MacEwen‘s Small Animal Clinical Oncology. https://doi.org/10.1016/B978-1-4377-2362-5.00018-3
- Kiupel, M., et al. 2011. Proposal of a 2-tier histologic grading system for canine cutaneous mast cell tumors to more accurately predict biological behavior. Veterinary Pathology. https://doi.org/10.1177/0300985810386469
- Smedley, R., et al. 2011. Prognostic markers for canine melanocytic neoplasms: a comparative review of the literature and goals for future investigation. Veterinary Pathology. https://doi.org/10.1177/0300985810390717
- Villalobos, A., and Kaplan, L. 2018. Canine and Feline Geriatric Oncology: Honoring the Human-Animal Bond. John Wiley & Sons.
- Withrow, S., Vail, D., and Page, R. 2020. Withrow and MacEwen‘s Small Animal Clinical Oncology, 6th Edition. Saunders.
