Dog Skin Cancer: How It’s Diagnosed and Treated

Four Minutes
May 31, 2024

You’ve likely heard of skin cancer affecting humans. But can dogs get skin cancer? Unfortunately yes, but diagnosing and treating skin cancer early on can provide a good outcome for pups. Keep reading for our guide to dog skin cancer.

MetLife Pet Insurance can help reimburse vet bills for skin cancer diagnoses and treatments. Get your free policy quote.

Types of Skin Cancer in Dogs

Tumors form due to an abnormal growth of cells and may be benign (not cancerous) or malignant (cancerous). Benign skin tumors don’t spread and are typically easy to surgically remove. Malignant skin tumors in dogs can be invasive and spread to other areas of the body — including tissues and organs.1

Not all cancerous tumors on dogs’ skin appear the same, and some may even look like generally harmless warts, cysts, or lipomas (fatty growths). Let’s take a closer look at some of the more common types of skin cancer in dogs.

Squamous cell carcinoma

Squamous cell carcinoma in dogs is the most common form of skin carcinoma and can be categorized as either skin squamous cell carcinoma or subungual squamous cell carcinoma.1

Skin squamous cell carcinomas typically develop in older dogs on their lower legs, abdomen, head, and backside. They can appear as firm, raised, open-sore lumps or may grow like a wart. Bloodhounds, basset hounds, and standard poodles are more at risk as well as short-haired, white-skinned dog breeds — such as beagles, pit bulls, Dalmatians, and bull terriers. Before a dog develops this tumor, they commonly develop discolored, thickened skin patches known as solar keratosis.1

Subungual squamous cell carcinomas develop under the nail, typically in dark-haired dogs or breeds like standard poodles, Gordon setters, Kerry blue terriers, schnauzers, Scottish terriers, and briards. Dogs could experience lameness, infection, or the loss of a nail with these tumors, which may spread to surrounding tissues and organs.1

Mast cell tumors

Mast cell tumors are typically the most common malignant skin tumors found on dogs, and they occur mostly in older pups. The legs, chest, and lower abdomen are where these tumors are usually found. Boxers, pugs, Boston terriers, and Rhodesian ridgebacks may be more prone to developing these cancerous tumors. They typically vary in size and growth and may show up as a soft or solid lump.1

Mast cells release histamines and other chemicals involved in the allergic reaction process. Because of this, dogs with mast cell tumors may also have stomach ulcers or show signs of toxin release in their body.1


Fibrosarcomas are a type of soft tissue sarcoma that vary in size and appearance, typically showing up on a dog’s legs and trunk. These tumors grow fast and may display as lumpy or firm and fleshy, depending on how deep under the skin the tumor originates. Doberman pinschers, Brittany spaniels, golden retrievers, Irish wolfhounds, and Gordon setters may be more prone to developing fibrosarcomas. Not only can they be fast-growing, but they also tend to be invasive and may spread to tissues around the tumors.1

Malignant melanomas

Melanomas are dark-pigmented growths that could display as flat or raised bumps, or come in spots or patches. They’re more commonly found to be benign and not concerning, but malignant melanomas may develop in older dogs — with schnauzers and Scottish terriers being more at risk. Malignant melanomas commonly show up as raised, open-sore lumps on a dog’s lips, mouth, and underside where there’s less fur, or as swelling on the toenail beds.1


A histiocytoma is typically a benign skin tumor commonly found in younger dogs that, on its own, isn’t usually cause for concern. But we’re mentioning it here because a single histiocytoma can become a problem if it starts spreading and becomes systemic histiocytosis. Bernese mountain dogs are highly susceptible to this form of the disease as well as malignant histiocytosis — which originates in their internal organs instead of their skin.1

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Symptoms of Dog Skin Cancer

If a dog has skin cancer, the signs they show can vary based on the type of cancer and location of the tumor. However, some common symptoms of skin cancer in dogs can include:1,2

  • Lumps or bumps on or under the skin
  • Tumors that change size or shape, or begin to ulcer
  • Swelling
  • Bleeding from body openings
  • Difficulty eating, breathing, or getting around
  • Wounds that won’t heal
  • Sudden weight changes
  • Diarrhea and vomiting that won’t stop

Since cancerous tumors may be easily confused with benign growths, bringing your dog to the vet for a physical exam can help diagnose them and potentially put worry at bay.

Diagnosing Dog Skin Cancer

There are many tests and advanced imaging that can help diagnose skin cancer in dogs. A tumor’s type may be confirmed through fine needle aspiration, which takes a sample of cells using a needle. Taking a small tissue sample — aka a biopsy — can provide more information on whether a tumor is benign or malignant.1,2

Other diagnostics can include blood work, X-rays, ultrasounds, computed tomography (CT) scans, magnetic resonance imaging (MRIs), and positron emission tomography (PET) scans. These help provide a larger picture of the tumor’s effects on the body and possible treatment options.2

Treating Skin Cancer in Dogs

Treatment for dog skin cancer can depend on the type of cancer, location, and stage, but prognosis is usually better if the cancer is caught early on.1,2 Treatment methods typically include surgery, chemotherapy, radiation therapy, or a combination.1 The table below shows some of the most common forms of treatment for each type of skin cancer and prognosis.1

Type of Cancer

Treatment Method


Squamous cell carcinoma

Surgical removal

Late diagnosis and recurrence of the original tumor can decrease survivability.

Mast cell tumors

Surgical removal, radiation therapy, and chemotherapy

Large, rapid-growth tumors and those not completely surgically removed have a worse prognosis.


Surgical removal, then follow-up radiation therapy and chemotherapy

Complete removal and additional therapy can prolong quality of life, but recurrence is common.

Malignant melanomas

Surgical removal, potential removal of toe or jaw portion if affected

Early treatment is critical due to rapid spreading; survival may range from 1 – 36 months.


Chemotherapy and possibly other drugs

Depending on the type, it can be progressive and terminal.

If your pup’s quality of life is poor before or after treatment, or the type or stage of cancer doesn’t have a good prognosis, euthanasia may be considered. Talk with your vet or veterinary oncologist about which treatment options are best for your dog.

The loss of a pet is never easy. That’s why we do what we can to help relieve stress during this time of transition with insurance coverage for euthanasia, burial, and cremation services, as well as grief counseling.3

Preventing Dog Skin Cancer

The exact cause of your pup’s cancer may not be known, but viruses, solar radiation, chemicals, hormonal abnormalities, and genetics can all play a part in causing skin cancer in dogs.1 While we can’t completely prevent cancer, we can help protect our dogs from those external factors that may put them at risk for developing skin cancer.

Bringing your dog in for routine exams could help catch cancer earlier, and it can be a good idea to bring them to the vet if you notice any new growths or changes in existing growths.

MetLife Pet May Help Cover Cancer Costs and More

Whether it’s during a routine checkup or a diagnostic exam, getting a cancer diagnosis can be difficult emotionally and financially. The average cost of a vet visit for cancer is $725, and it can vary based on the treatment required and frequency — which could stretch out over months or years.4

Having a plan in place for unexpected vet expenses can help ease the financial burden. A dog insurance policy from MetLife Pet could be an essential part of this plan. We can typically reimburse up to 90% on vet bills for covered cancer expenses.5 Take Bently, a 10-year-old dog from Illinois, for example. He was diagnosed with fibrosarcoma and promptly had surgery to remove it. The vet bill cost nearly $2,000, but his parents were reimbursed close to $1,800 because of their MetLife Pet policy.6

We also provide financial peace of mind for routine care with our optional Preventive Care plan — so those routine exams that may help catch cancer earlier can be covered. And if you want a vet’s quick advice on a growth you noticed on your dog, take advantage of our free 24/7 vet chat7 through our mobile app for policyholders. Protect your pet today so you can get them the care they need when the unexpected happens. Get your free MetLife Pet Insurance quote in just a few minutes.

A MetLife Pet Policy May Help You Cover Costly Cancer Expenses

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**As with any insurance policy, coverage may vary. Review our coverage and exclusions.

1 “Tumors of the Skin in Dogs,” Merck Veterinary Manual

2 “Cancer in Pets,” American Veterinary Medical Association

3 Grief Counseling services are provided through an agreement with TELUS Health, an unaffiliated third-party service provider. Grief counseling services provided by TELUS Health are separate and apart from the insurance provided by MetLife Pet. Not available to NY residents.

4 Vet costs based on MetLife Pet internal claims data from June 2023 to December 2023, unless otherwise noted.

5 Reimbursement options include: 50%, 70%, 80% and 90%. Pet age restrictions may apply.

6 All claims paid amounts are based on MetLife Pet internal claims data from July 2023. This example is for illustrative purposes only. This is based on a policy with a $300 deductible and 90% reimbursement. The pet policy issued by Metropolitan General Insurance Company is the governing document with respect to all matters of insurance. The specific facts of each claim must be evaluated in conjunction with the provisions of the applicable Policy to determine coverage in each individual case.

7 Virtual veterinary services are available through the MetLife Pet App and are provided entirely by AskVet, a third-party partner; MetLife Pet is not responsible for any pet guidance or advice provided or taken. Veterinarians providing virtual veterinary services cannot prescribe medication or answer questions about the pet policy.

Coverage issued by Metropolitan General Insurance Company (“MetGen”), a Rhode Island insurance company, headquartered at 700 Quaker Lane, Warwick, RI 02886. Availability is subject to regulatory approval. Coverage subject to restrictions, exclusions and limitations and application is subject to underwriting. See policy or contact MetLife Pet Insurance Solutions LLC (“MetLife Pet”) for details. MetLife Pet is the policy administrator. It may operate under an alternate or fictitious name in certain jurisdictions, including MetLife Pet Insurance Services LLC (New York and Minnesota), and MetLife Pet Insurance Solutions Agency LLC (Illinois).

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