Cancer in Dogs: What You Need to Know 

Early prevention, detection, and treatment is key.

cancer in dogs

Your dog isn’t just a pet. They’re an important member of your family, and you want them to have the best, healthiest, and longest life possible. So, if you hear that your dog has cancer, it can be a devastating and frightening time. 

If your dog receives that scary Big C diagnosis, you’re far from alone. A research study on domestic dogs and cancer found that cancer is the leading cause of death in dogs over the age of 10. The study found that half of older dogs developed cancer, and one in four eventually passed away from the disease. 

While it’s upsetting to hear that your dog is sick, there are treatments available that you can discuss with your dog’s vet. There are also ways that you can help to keep your dog comfortable throughout the treatment process. And planning ahead, by getting pet insurance for your dog, can also protect against daunting bills in the future.

Here’s what we’ll cover:

Signs and symptoms of cancer in dogs

Common signs of cancer in dogs vary, but here are some things to watch out for:

  • Swellings, like swollen lymph nodes (which are located under the jaw, in front of the shoulder, and behind the knee in dogs)
  • Changes in color to the skin
  • Unusual lumps and bumps
  • A wound that just doesn’t heal up correctly
  • Unexplained loss of appetite and weight loss
  • Unusual bleeding and lameness can also occur

But sometimes, there are almost no observable signs of cancer at all. If you notice that your dog just doesn’t seem like themselves, that they’re unusually quiet, or that they just seem to be slowing down, it’s a good idea to make an appointment with your vet to get your best friend checked out. Early detection is key.

Benign vs. cancerous tumors 

If your dog develops a tumor, try not to panic—but we understand that’s easier said than done! No one enjoys visiting the doctor and hearing that word thrown around.

As with humans, tumors can be benign or malignant. To determine what type of tumor your dog has, your vet may perform a test called a fine needle aspirate, or they might biopsy the tumor by removing a small part of it. 

A benign tumor won’t spread throughout your dog’s body. These non-cancerous tumors aren’t invasive and can be surgically removed without much fuss beyond that. Your vet might decide that it doesn’t need treatment at all.

If your dog’s tumor turns out to be benign, that’s great news—celebrate with extra treats and snuggles.

Malignant tumors, on the other hand, are cancerous. These tumors can spread throughout the body and are harmful to your dog’s health. 

If your vet suspects that the tumor might be malignant, they will often surgically remove the tumor, as well as the tissue around it. Taking this extra tissue can help to reduce the chance of any cancer cells being left behind to regrow. 

If the tests reveal that your dog’s tumor was malignant, your vet will discuss treatment options with you. If the tumor was removed with “clean” margins, there may not be any cells left to regrow, which is the best-case scenario. 

Common types of cancer in dogs 

According to the Animal Cancer Society, there are several common canine cancers that you should know about.

Bone cancer

Also called osteosarcoma, bone cancer is very painful. It typically occurs in your dog’s larger bones, and is common in breeds like Dobermans, Golden Retrievers, Great Danes, Rottweilers, and German Shepherds. 


Melanoma tumors are found on your dog’s skin, but these tumors are often benign. Malignant melanoma tumors spread rapidly and are difficult to treat. The tumors often occur in and around the mouth and feet. 


Lymphoma is very common in dogs. There are more than 30 types of lymphoma, and these types of cancers originate in white blood cells. 


Hemangiosarcoma tumors often grow in the spleen, but can also be found on the liver and heart. This cancer is often fatal without treatment. It requires emergency surgical removal, and is notoriously difficult to treat. 

Mast cell tumors

Mast cell tumors typically occur just underneath or on the skin. They can be tricky to remove, depending on their location—but with early detection, this type of cancer can often be cured. 

Treatments for cancer in dogs 

Just as humans can undergo cancer treatments like radiation therapy, surgery, and chemotherapy, dogs have access to those same types of treatments. Cancer treatments might not be available at your local vet’s office, so you might need to travel to an animal hospital with an oncology department that offers them. 

In addition, according to the U.S. Food & Drug Administration (FDA), there are currently three FDA-approved drugs to treat cancer in dogs, and one drug that is conditionally approved:

  • Palladia was approved to treat mast cell tumors in 2009
  • Stelfonta was approved to treat mast cell tumors in 2020
  • Tanovea-CA1 was approved to treat lymphoma in 2021
  • Laverdia-CA1 was conditionally approved to treat lymphoma in 2021

Your vet can also discuss options for managing your dog’s pain. This might include pain medications and therapy, like acupuncture.

How much does it cost to treat cancer in dogs?

The cost of treating your dog for cancer will vary depending on the treatment needed, where you live, and where you take your dog to get the treatment.

According to the Veterinary Cancer Society, treating your dog for cancer can get expensive quickly.

  • An initial cancer consultation can cost $150 to $250
  • A full course of chemotherapy costs anywhere between $8,000 to $10,000
  • A course of radiation treatments costs anywhere from $5,000 to $10,000

Consider this: The testing, surgery, chemotherapy, and follow-up appointments for soft tissue sarcoma can set you back about $40,000 in total. 

Cancer treatments can be prohibitively expensive, but if your pup is covered with pet insurance, it can help take the bite out of expensive vet bills.

For example, if your dog is diagnosed with cancer and they have a Lemonade Pet policy, treatments like chemotherapy will likely be covered (keeping in mind things like your deductible and co-insurance). Your policy can also help pay for diagnostics, so if there’s a suspicious lump that you want to have checked out by your vet, your policy could cover things like cytology, needle aspiration, or biopsy. 

But remember, if you notice a lump or bump, other changes, or tests show abnormalities before you sign up for pet insurance (or during their waiting period for illnesses, which varies by state), your pet’s cancer treatments won’t be covered, because it would be considered a pre-existing condition. This is why it’s so important to get pet insurance before you notice anything wrong—if you wait, it may be too late to get coverage for these conditions.

Also, keep in mind that experimental and homeopathic treatments for cancer or other illnesses would not be covered under a Lemonade Pet policy. 

How to prevent cancer in dogs

We know that thinking about your pup getting the Big C feels downright depressing, but there are many ways that you can help to prevent cancer in your dog, starting today. 

  • Spay or neuter your dog. Spayed female dogs won’t risk cancer to their reproductive system or mammary glands, and spayed males are at basically zero risk for developing testicular cancer. 
  • Minimize time in the sun. Prolonged exposure to the sun’s rays can lead to skin cancer, especially on areas of your dog’s body with little hair, like their tummy. Try to cut down on long periods of time when your dog is out in direct sunlight. 
  • Don’t smoke near your pup. Just like humans can develop cancer from secondhand smoke, your dog can also get cancer if you smoke in the house or car with them.
  • Carefully choose a breeder. If you’re going to get a puppy from a breeder, choose a breeder who screens their breeding dogs for common cancers. This is particularly important in dog breeds that are prone to cancer, including Boxers, German Shepherds, and Golden Retrievers. 
  • Keep your dog at an ideal weight. Obesity is unhealthy for dogs and can lead to many common diseases, like diabetes. But did you know it can increase your dog’s chance of getting cancer? It’s just one more reason to focus on keeping your furbaby fit and healthy. 

Before we go…

Hopefully you and your fur fam never have to face a cancer diagnosis. But if you do, remember that there are many treatment options to explore. Your vet can help you to identify potential treatments and give your best friend the best shot at spending many more healthy years by your side. You are not alone. 

We know this can be hard to think about and even more difficult to face. Take a breath, and give your pup some belly rubs from us, will you? Your dog is lucky to have you by their side. 

Paige Cerulli

Paige Cerulli is a lifelong animal lover and a certified equine massage therapist. She works as a copywriter and content writer, and her work has appeared on American Veterinarian, Northeast Equestrian Life Magazine, Business Insider, and more. Paige lives in Western Massachusetts where she shares her life with three cats, three horses, a flock of ducks, and several foster animals.


Please note: Lemonade articles and other editorial content are meant for educational purposes only, and should not be relied upon instead of professional legal, insurance or financial advice. The content of these educational articles does not alter the terms, conditions, exclusions, or limitations of policies issued by Lemonade, which differ according to your state of residence. While we regularly review previously published content to ensure it is accurate and up-to-date, there may be instances in which legal conditions or policy details have changed since publication. Any hypothetical examples used in Lemonade editorial content are purely expositional. Hypothetical examples do not alter or bind Lemonade to any application of your insurance policy to the particular facts and circumstances of any actual claim.