Melanoma in dogs behaves very differently depending on where it grows. Dark growths on a dog's haired skin are usually benign (melanocytomas), while melanomas in the mouth, on the lips and in the nail bed are usually malignant and can spread.1,2,3 Mouth (oral) melanoma is the most common mouth tumor in dogs, and most affected dogs are older, around 11 to 12 years.4,5 Not every melanoma is dark: about one-third of mouth melanomas have no pigment, so any new lump needs a needle sample or biopsy.6,7 Treatment is mainly surgery, often with radiation, and outlook ranges from a cure for benign skin tumors to months for large mouth tumors that have spread.3,8,1
See your vet promptly if your dog has:
- A new, growing, bleeding or ulcerated dark lump, or a pink lump that keeps growing9,7
- A lump on the gums or palate, bad breath, drooling, bleeding from the mouth or trouble eating10,2
- A swollen toe, a loose or lost nail, or limping that doesn't settle2,11
- Swollen lymph nodes under the jaw or in front of the shoulder5
What the Research Says
- Tumor size is the strongest guide to outlook. A 2024 review pooling 459 mouth melanomas found median survival of 589 days for tumors under 2 cm, 251 days for 2 to 4 cm and 173 days for tumors over 4 cm.8
- Normal-sized lymph nodes can still hold cancer. About 40% of dogs with normal-sized nodes have microscopic spread, so specialists sample the nodes regardless of size.4,3
- The vaccine is safe, but its benefit is unproven. A 2022 review found no definitive proof that the licensed melanoma DNA vaccine lengthens survival and called for a randomized trial.12
- New international guidelines. A 2024 consensus from specialists in Europe, the US and Japan set out staging and treatment standards for dogs and cats.3
Melanoma Depends on Where It Grows
| Site | How it usually behaves | Typical treatment |
|---|---|---|
| Mouth and lips | Usually malignant; often spreads to lymph nodes, then lungs6,1 | Surgery, often with radiation; staging first6,3 |
| Haired skin | Usually benign (melanocytoma), but some are malignant; breed matters1,9 | Removal, which cures benign tumors1,7 |
| Toe and nail bed | More likely malignant than skin tumors; nail-bed tumors are considered malignant3,13 | Toe amputation3,14 |
| Eye | Usually benign; rarely spreads15 | Monitoring, laser or eye removal; see eye tumors in dogs3,15 |
What Melanoma Looks Like on Dogs
Most melanomas are dark (black, brown or gray) raised lumps, but some are pink or skin-colored. About 17% of melanomas overall lack pigment.7,16 On the skin, small, smooth, deeply pigmented lumps that move freely are more often benign, while malignant ones are usually larger than about 2.5 cm (1 inch) and may ulcerate, become infected or grow quickly.9 In the mouth, look for dark or pink nodules on the gums, palate, lips or tongue. Mouth tumors can look small yet extend into the bone.10,7
Appearance alone can't tell a benign growth from melanoma. Your vet will take a needle sample (aspirate) and usually a biopsy.7,3
Growths that can be mistaken for melanoma
| Lookalike | Why it can look similar |
|---|---|
| Benign melanocytoma | Same pigment cells; dark and slow-growing; far more common on the skin than malignant melanoma1,7 |
| Basal cell tumor | Firm lump that is "sometimes dark in color"7 |
| Hemangioma | Red to black lump like a blood blister7 |
| Epidermal hamartoma | Dark, pointed bumps, mostly in puppies7 |
| Warty dyskeratoma | A lump with a dark dot in the center7 |
| Toe squamous cell carcinoma or infection | Swollen toe, lost nail and bone damage on X-rays, often in large black-coated dogs13,14 |
| Iris freckles | Flat dark spots in the colored part of the eye15 |
For other skin growths, see lumps and bumps on dogs.
Mouth (Oral) Melanoma
Oral melanoma makes up about 31% to 42% of mouth tumors in dogs. Signs include bad breath, drooling, bleeding, loose teeth, dropping food, facial swelling and not wanting the head touched.4,10,2 Chow Chows, Cocker Spaniels, Dachshunds, Golden Retrievers, Poodles and Scottish Terriers are among the breeds at higher risk, and dogs with heavily pigmented gums may be more prone.10,3,4
Staging
Stage is set mainly by tumor size: stage I is under 2 cm (less than an inch), stage II is 2 to 4 cm, and stage III is over 4 cm or has spread to lymph nodes.4,3 Staging usually includes three-view chest X-rays, samples from the jaw lymph nodes even if they feel normal, and CT before surgery.6,3
Treatment
- Surgery is generally the best first option, often removing part of the jaw along with nearby lymph nodes. Most dogs eat and look well afterward.6,5 See mouth cancer in dogs for jaw surgery.
- Radiation shrinks over 80% of visible mouth melanomas, though about half regrow. It is a standard option when surgery isn't possible or leaves cells behind.3,4,6
- Chemotherapy shrinks some tumors, with responses in roughly 30%, but hasn't been shown to lengthen survival after surgery.3,2,6
- The melanoma DNA vaccine is USDA licensed for stage II and III oral melanoma after the tumor in the mouth has been controlled. It is safe, with mainly brief soreness or bruising at the injection site.17,18,12 Some studies suggest it helps and others found no clear benefit, and the licensing study had no control group.12,8,17 It treats existing cancer and does not prevent melanoma.11
- A checkpoint-inhibitor antibody (an immune treatment) is now conditionally licensed for some dogs with stage II and III melanoma and is available only through veterinary oncologists.19,18 In its safety study, tiredness, poor appetite and diarrhea were commonly reported, though the study did not show how many were caused by the treatment.20
Skin Melanoma
Melanocytic tumors make up about 5% to 7% of skin tumors in dogs, at an average age of about 9.9 Most turn out to be benign melanocytomas, and removing them cures the dog.1,2 Breed affects the odds: about 75% of these tumors are benign in Dobermans and Miniature Schnauzers, while about 85% are malignant in Miniature Poodles.9 Dogs with dark skin or black coats are at higher risk, and the role of sun exposure isn't known.11
The pathology report grades how aggressive the cells look, using terms such as mitotic count, nuclear atypia and Ki-67. Your vet will explain what your dog's results mean.3,9 Low-grade tumors removed with clean margins are often cured.3 Dogs with malignant skin melanoma under 4 cm live a median of about 12 months, compared with about 4 months for larger tumors.9
Toe and Nail Bed Melanoma
Melanoma causes almost a quarter of toe tumors. It can destroy bone, causing swelling, pain, licking, a loose nail and limping.11,2 Studies disagree on how often toe melanocytic tumors are benign, from about half to about 1 in 7, but tumors under the nail are considered malignant.13,3 Squamous cell carcinoma and infection look very similar, so a biopsy is needed.13,14
Treatment is amputation of the toe, which rarely causes long-term lameness.14,3 About 30% of dogs already have spread when the tumor is found. After amputation, dogs without spread live a median of about 12 months, and the outlook is shorter if the cancer has already spread.13,3,14
Eye Melanoma
Melanoma inside the eye (uveal melanoma) is the most common eye tumor in dogs, but about 80% are benign and fewer than 5% spread. Golden and Labrador Retrievers and German Shepherds are predisposed.15 Melanomas on the conjunctiva (the pink tissue around the eye) are more often malignant.3 See eye tumors and eyelid growths in dogs.
Signs That Melanoma Has Spread
Malignant melanoma usually spreads first to nearby lymph nodes and then to the lungs, and sometimes the liver.6,2 Up to about 3 in 4 dogs with mouth melanoma develop spread over time.4,6 Watch for:
- Swollen lymph nodes under the jaw or in front of the shoulder5
- Coughing, tiredness and a poor appetite5
- Regrowth at the surgery site2,4
Many dogs show no signs of spread until late, so recheck chest X-rays or CT are part of follow-up.3
Life Expectancy
| Type and treatment | Typical median survival |
|---|---|
| Benign skin melanocytoma, removed | Usually cured1 |
| Malignant skin melanoma | About 12 months if under 4 cm; about 4 months if larger9 |
| Mouth melanoma, untreated | About 2 months (65 days)4,5 |
| Mouth melanoma under 2 cm, surgery | About 1 to 2.5 years (511 to 874 days in older studies; about 12 to 14 months in more recent reports)3,8 |
| Mouth melanoma over 4 cm or spread | About 5.5 to 7 months (168 to 207 days in studies)8,3 |
| Toe melanoma, amputation | About 12 months13,3,14 |
| Eye melanoma | Usually good15 |
These are medians from groups of dogs. Your vet or oncologist can estimate your dog's outlook. When treatment is no longer helping, see quality of life and when to say goodbye.
How Much Does Melanoma Treatment Cost?
| Item | Approximate US cost |
|---|---|
| Diagnosis (needle sample or biopsy) | About $500 or less, more with full staging16 |
| Toe amputation | $500 to $1,00016 |
| Mouth surgery involving bone | $2,000 to $5,00016 |
| Radiation for a mouth tumor | $5,000 to $10,00016 |
| Chemotherapy | $1,000 to $3,00016 |
| Melanoma vaccine | $1,000 to $1,500 per dose; several doses are needed16 |
Figures are approximate, from Embrace Pet Insurance (2023). Aggressive cases can exceed $10,000. Prices vary widely by region and hospital, so ask for a written estimate. See dog cancer treatment for ways to manage costs.16
Frequently Asked Questions
Is melanoma in dogs always cancer?
No. Most dark growths on haired skin are benign melanocytomas that are cured by removal. Mouth and nail-bed melanomas are usually malignant.
What does melanoma look like on a dog?
Usually a dark raised lump, but some are pink. Only a needle sample or biopsy can confirm it.
How long can a dog live with oral melanoma?
Without treatment, about 2 months. After surgery, dogs with small tumors often live a year or more, sometimes over 2 years, while large tumors or spread usually mean about 5 to 7 months.
Does the melanoma vaccine work?
It is safe and licensed for some mouth melanomas, but studies disagree on how much it helps. Ask your oncologist whether it fits your dog's plan and budget.
Can melanoma in dogs be prevented?
There is no known way to prevent it. Checking your dog's mouth, skin and toes and having new lumps tested gives the best chance of early treatment.
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Sources and further reading
This article was rewritten and fact-checked on October 29, 2026 against current veterinary references and specialist guidelines:
- Villalobos AE. Tumors of Melanocytic Origin in Animals. Merck Veterinary Manual, Professional Version, updated November 2024.
- Comprehensive Cancer Care Service, Penn Vet Ryan Hospital. Melanoma in dogs. University of Pennsylvania, November 2017.
- Polton G, Borrego JF, Clemente-Vicario F, Clifford CA, Jagielski D, Kessler M, Kobayashi T, Lanore D, Queiroga FL, Rowe AT, Vajdovich P, Bergman PJ. Melanoma of the dog and cat: consensus and guidelines. Frontiers in Veterinary Science 2024;11:1359426.
- Veterinary Society of Surgical Oncology. Oral Melanoma. VSSO, 2019.
- Molinaro A. Canine oral melanoma. BluePearl Pet Hospital, October 2, 2019, updated November 17, 2023.
- American Animal Hospital Association. Table 1.1: Common cancers of dogs. 2026 AAHA Oncology Guidelines for Dogs and Cats, 2026.
- Villalobos AE. Tumors of the Skin in Dogs. Merck Veterinary Manual, Pet Owner Version, reviewed June 2018, updated April 2026.
- Song E, et al. Risk stratification scheme based on the TNM staging system for dogs with oral malignant melanoma centered on clinicopathologic presentation. Frontiers in Veterinary Science, 2024.
- Veterinary Society of Surgical Oncology. Skin Melanoma - Canine. VSSO, 2019.
- Llera R, Bellows J, Pinard C. Oral tumors in dogs: melanomas. VCA Animal Hospitals, March 2023.
- Llera R, Stoewen D, Pinard C. Melanomas of the skin and toes. VCA Animal Hospitals, updated January 30, 2023.
- Pellin MA. The use of [a canine melanoma DNA vaccine] in veterinary patients: a review of the literature. Veterinary Sciences, 2022.
- Veterinary Society of Surgical Oncology. Digit Tumors. VSSO, 2019.
- Liptak JM. Digit tumors. animalcancersurgeon.com, updated March 6, 2017.
- Weir M, Stoewen D, Pinard C. Eye tumors: melanoma in dogs. VCA Animal Hospitals, May 2023.
- Khuly P. Melanoma. Embrace Pet Insurance, updated July 27, 2023.
- USDA APHIS Center for Veterinary Biologics. Summary of studies supporting USDA product licensure: canine melanoma vaccine, DNA. Compiled May 16, 2024.
- American Animal Hospital Association. Table 5.1: Overview of antineoplastic chemotherapy and immunotherapy agents commonly used in veterinary medicine. 2026 AAHA Oncology Guidelines for Dogs and Cats, 2026.
- American Animal Hospital Association. Therapeutic modalities: immunotherapy. 2026 AAHA Oncology Guidelines for Dogs and Cats (web section), 2026.
- USDA APHIS Center for Veterinary Biologics. Summary of studies supporting USDA product licensure: [a canine checkpoint-inhibitor antibody] (safety study). Compiled December 6, 2022.
About this article
Last updated : fully rewritten as a complete melanoma guide using the 2024 international melanoma consensus, the 2026 AAHA Oncology Guidelines, the Veterinary Society of Surgical Oncology, the Merck Veterinary Manual, the University of Pennsylvania, USDA licensing summaries and studies published 2022 to 2024; added the research summary, site table, lookalikes, mouth, skin, toe and eye sections, life expectancy and cost tables, key takeaways and FAQ.
This page is for general information and is not a substitute for an exam by your veterinarian.
