Cancer in Dogs: Types, Symptoms & Treatments Guide

4 min read
Jan 22, 2024

Can dogs get cancer? You might be surprised to learn that cancer in dogs is common — so common, in fact, that roughly one in four dogs will develop some form of cancer in their lifetime. It’s a risk that increases after 10 years of age.1 But some cancers are more common than others.

Read on to learn about the basics of canine cancer, symptoms of cancer in dogs, and how these common cancers are treated.

Common Dog Cancer Terminology

Talking about dog cancer with your veterinarian can be overwhelming, and terminology may be difficult to process as you grapple with a difficult diagnosis. But it’s important to understand exactly what your vet is telling you. The type of growth your dog has will determine the type of cancer treatment your dog will receive. There are three important terms to understand when discussing this diagnosis: tumor, neoplasia, and cancer:1

  1. Tumor: Sometimes called a “mass,” a tumor is the actual swelling of the physical appearance of the neoplasm that can either be benign or malignant.1
  2. Neoplasia: An uncontrolled growth of cells or tissues creates what’s known as a neoplasm.1 Sometimes, this takes the form of a tumor that looks or feels like a firm bump. Other times, the neoplasm isn’t firm to the touch. They tend to be benign and slow growing, and they rarely spread throughout the body.
  3. Cancer: This is a term used to describe malignant tumors and neoplasms that have metastasized — meaning they can spread by invading healthy tissues around the cancerous mass.1

These terms aren’t exhaustive, but it’s enough to get you started so you can better understand your dog’s diagnosis.

Pet Insurance May Help Cover Cancer Costs

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Symptoms and Signs of Cancer in Dogs

Recognizing cancer can be tricky because the symptoms can often look like other issues. However, it may be time to ask your vet to take a closer look if you see a combination of these symptoms in your dog:2

  • Lethargy or lack of interest in playing
  • Abnormal swelling
  • Fever
  • Loss of appetite or weight
  • Difficulty eating or drinking
  • Difficulty breathing
  • Excessive vomiting or diarrhea
  • Inflammation
  • Bleeding or discharge from the mouth, nose, or another body opening
  • Bad odor
  • Trouble going to the bathroom
  • Lumps, bumps, or discolored skin
  • Mobility issues

This list doesn’t encompass every symptom, but it captures some of the most common among dog cancers, so you can speak to your vet if your pup is experiencing any or all of them. Your vet can walk you through the specifics of the type of cancer your pet has after diagnostic testing.

How To Diagnose Cancer in Dogs

Once your vet confirms the symptoms that you’re witnessing at home, they will conduct diagnostic tests to uncover a root cause. The tests will help them figure out if the mass is cancerous and, if so, what kind of cancer your dog has. This will likely include blood work, fecal samples, and a physical exam. Afterward, your vet may recommend a biopsy to collect tissue samples. They may also refer you to a veterinary radiologist for a CT scan, MRI, or other digital scans to help locate the tumor.

Treatment Options for Cancer in Dogs

Once your vet has confirmed their diagnosis, they will provide you with options for next steps. They may recommend one type of treatment to focus on or a combination of options, if necessary:

  • Chemotherapy: This involves a regimen of powerful chemicals meant to kill cancerous cells faster than they can multiply.3 The chemotherapy may be administered directly to the cancerous mass with injections or intravenously to fight cancer throughout the body.
  • Radiation therapy: A specialist uses controlled radiation to damage and kill off cancer cells before they can metastasize.4
  • Surgery: Sometimes, cancer can be removed via surgery.5 If this is done early enough, it can prevent the cancer from spreading.
  • Drugs: According to the FDA, there are three drugs approved to treat cancer in dogs: Palladia tablets and Stelfonta injections for treating mast cell tumors, and Tanovea-CA1 injections for treating lymphoma. A fourth drug, Laverdia-CA1 (tablets), was conditionally approved to treat lymphoma in 2021.6
  • Immunotherapy: With this newer treatment, a vaccine that’s created using your dog’s tumor cells is injected into your dog in an effort to train their immune system to attack the cancer cells directly.7 This may be able to help your dog’s immune system keep up with the rapid pace of cancer cell proliferation.

Types of Cancer in Dogs

There are many different types of cancer in dogs, just like there are many different types of cancer in humans. Here are the top seven types of dog cancers, dog tumors, and neoplasia in dogs and what they look like.

7 common cancers in dogs

Type Common Symptoms Treatment

Melanoma: skin cancer8

Lumps and swollen lymph nodes


Osteosarcoma: bone cancer9

Sudden lameness and bone swelling

Chemotherapy and limb amputation

Adenocarcinoma: lung cancer10

Coughing, lethargy, and respiratory distress

Surgery or chemotherapy

Basal tumors: skin cancer11

Raised, hairless mass on the head, neck, or shoulder


Lymphoma: blood cancer

Swollen lymph nodes, lethargy, loss of appetite

Chemotherapy, potentially surgery or radiation as well

Mammary tumors: breast cancer12

Mass on the abdomen

Surgery or chemotherapy

Hemangiosarcoma: blood tissue cancer13

Surface bumps, lethargy, internal bleeding

Surgery, chemotherapy, or radiation

What causes cancer in dogs?

When it comes to most cancers, it can be hard to narrow down the exact cause. Dog cancer can arise from any number of factors, including:14

  • Genetics
  • Carcinogenic materials
  • Old age
  • Viruses
  • Sexual transmission

While many of these factors are out of our control as pet owners, there are some steps you can take to help mitigate your pup’s risk.15 Spaying and neutering are known to help reduce the risk of cancer and provide other health benefits. Maintaining an environment free of carcinogens, such as cigarette smoke and pesticides, can also help. Finally, a healthy diet and routine care can give your dog a better chance of fighting off disease in general, including cancer.15

How long will a dog live with cancer?

The prognosis of dog cancers can vary depending on the type.16 Dogs with a particularly aggressive cancer may be given only a few months, even with treatment. Others may have longer. It’s important to keep in mind that a prognosis is the “best case scenario” estimation.

Weighing the pros and cons of treatment is a difficult decision. It may give your dog more time, but treatment may also come with considerable side effects that would reduce their overall quality of life. Only you know what’s best for your dog. Discussing options with your vet can help you make an informed choice that’s in your dog’s best interest.

Can Pet Insurance Help With Dog Cancer Expenses?

A cancer diagnosis in the family upends your life. The last thing any pet owner wants to worry about at that moment is money, but the cost of treatment can be prohibitively expensive. Chemotherapy can range from $150 to $600 per dose, and your dog may need multiple rounds for months at a time. Including diagnostic testing and follow-ups, you could end up paying as much as $8,000.17

A dog insurance plan could help cover the cost of your dog’s treatment. For example, MetLife Pet members in Wisconsin were reimbursed for the full cost of their pup’s hospitalization for an intestinal mass — nearly $7,000.15 Other members in Arizona had two-thirds of the cost of their dog’s tumor examination covered — a $2,000 value.18

Pet insurance can give you one less thing to worry about, while you focus on making the best decisions for your beloved companion. Learn more about how pet insurance works, or get a free quote today to get started.

Help Protect Your Pup From Major Illnesses

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

1 “Cancer in Pets,” American Veterinary Medical Association

2 “Cancer in Dogs: Signs and Symptoms to Watch Out For,” American Kennel Club

3 “Chemotherapy,” VCA Animal Hospitals

4 “Radiation Therapy,” VCA Animal Hospitals

5 “Cancer Surgery For Pets,” VCA Animal Hospitals

6 “My Dog Has Cancer, What Do I Need to Know?” FDA, 2021

7 “Immunotherapy treatment,” Cornell University College of Veterinary Medicine

8 “Melanoma Tumors in Dogs,” PetMD

9 “Bone Disorders in Dogs,” Merck Veterinary Manual

10 “Lung Cancer (Adenocarcinome) in Dogs,” PetMD

11 “Basal Cell Tumors,” VCA Hospitals

12 “Mammary Tumors,” American College of Veterinary Surgeons

13 “Medical Oncology: Hemangiosarcoma,” North Carolina Veterinary Hospital

14 “Causes of Cancer,” Merck Veterinary Manual

15 “Reducing the Risk of Cancer,” Merck Veterinary Manual

16 “Difficult decisions,” Cornell University College of Veterinary Medicine

17 “Chemotherapy in Dogs - Conditions Treated, Procedure, Efficacy, Recovery, Cost, Considerations, Prevention,” Wag!

18 All claims paid amounts are based on MetLife internal claims data from October 2022. Story altered for illustrative purposes.

Coverage issued by Metropolitan General Insurance Company (“MetGen”), a Rhode Island insurance company, headquartered at 700 Quaker Lane, Warwick, RI 02886, and Independence American Insurance Company (“IAIC”), a Delaware insurance company, headquartered at 11333 N Scottsdale Rd, Ste 160, Scottsdale, AZ 85454. 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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