Cancer in Dogs: Symptoms, Treatment & Survival Guide (Canada)

Dog cancer is now the main cause of canine death. According to the US FDA, cancer accounts for”almost half of the deaths of pets over 10 years of age.”¹ That is a sobering statistic. A study from the UK estimated that cancer is the leading cause of death in dogs for “more than 30% of dogs over one year of age.”² Dogs develop cancer at roughly the same rate as humans, while cats develop cancer less frequently.

For most dog owners, when cancer is diagnosed in your dog, you may feel like you have been hit with a sledgehammer and you are being asked to make an important health and financial decision immediately. However, like any major health decision, it is reasonable to ask your veterinarian a few more questions before making an immediate decision. Is your dog currently suffering or in severe pain, or do you have time to understand the diagnosis and evaluate your options? In many cases you do have time to step back, ask questions, and make the right decision for both your dog and your family.

This practical guide aims to help dog owners understand the most common types of cancer in dogs, what to do after diagnosis, treatment options and success rates, and whether there are realistic ways to support quality of life and possibly prevention.

Is It Worth Treating a Dog With Cancer

This is one of the most difficult questions a dog owner can face, and there is rarely a simple answer.

Veterinary oncology has advanced significantly over the past twenty years. Many cancers can now be treated or managed for meaningful periods of time. However, treatment is not always the right choice for every dog.

Several factors usually determine whether treatment is worth pursuing.

1. Type of Cancer – Some cancers respond well to treatment while others are far more aggressive.
2. The Stage of Disease – A tumor that is localized and detected early may be removable or manageable. A cancer that has already spread to multiple organs may have far fewer treatment options.
3. Dog’s Overall Health and Age – A younger dog in otherwise good health may tolerate treatment much better than a senior dog with multiple health conditions.
4. Another major consideration is quality of life. Veterinary oncology places strong emphasis on maintaining comfort. In many cases dogs tolerate chemotherapy significantly better than humans do, often experiencing fewer severe side effects. However treatment can still involve repeated veterinary visits, diagnostic tests, and stress for some animals.
5. Finally there is the financial reality. Advanced cancer care can cost thousands of dollars and not every family is prepared for that expense.

Many veterinarians remind owners that treatment decisions are not only about extending life but also about preserving the quality of the life your dog still has. Sometimes the right answer is aggressive treatment. Sometimes it is supportive care that focuses on comfort and good days.

How Long Will a Dog Live With Cancer?

One of the first questions most owners ask after hearing a cancer diagnosis is how much time their dog might have left.

Unfortunately there is no single answer. Survival time varies widely depending on the type of cancer, stage at diagnosis, treatment options pursued, and the overall health of the dog.

Veterinary researchers are increasingly studying the biological mechanisms that influence tumor growth and survival outcomes. Some of this research focuses on how cancer cells alter their metabolism to grow rapidly. Understanding how cancer cells use energy has opened new areas of investigation into treatments and nutritional approaches that may influence tumor metabolism.

While statistics provide general guidance, veterinarians often emphasize that quality of life is ultimately more important than survival numbers. Dogs do not measure time the way humans do. For many families, the goal becomes ensuring the time remaining is filled with comfort, enjoyment, and meaningful experiences.

Top 5 Steps to Take When Your Pet Has Been Diagnosed with Cancer

1. Take a deep breath and slow down. (Go for a walk if you need to collect your thoughts and emotions.)
2. Ask your vet the following questions:
   • What kind of canine cancer is it?
   • Is it localized or metastasized (spread to other areas)?
   • What stage is my dog’s cancer at? If the stage is not known, do we need to stage it especially if it has metastasized?
   • Is treatment recommended and what kind of treatment options are available?
   • How much does each option cost? (Please have it written out so you can reference later)
   • If treatment is not an option, how much pain is your pet in and is it safe to have your pet at home?
3. If your pet can go home, plan and do fun activities that they love and spend as much time as possible keeping in mind their energy level.
4. When quality of life becomes the priority. First spend a lot of quality time with your furry baby. Other things to consider include:
   • Sign up for either in-home euthanasia or at the vet after spending time with your loved furry baby.
   • Also, set up a cremation process if you want private cremation or talk to your vet about if they have a service available.
   • Remember the love and fun times you had, your dog would not want you to think any other way.
5. If treatment is an option, set up a plan with your vet and read our section below on supports such as diets and supplements to maintain muscle mass and appetite during treatment.

Early Signs of Cancer in Dogs Owners Should Never Ignore

One of the challenges with cancer is that clinical symptoms often appear slowly and may initially seem minor. Veterinarians commonly recommend paying attention to several warning signs that may indicate something more serious.

• Persistent lumps or swelling that continue to grow should always be evaluated. Not every lump is cancerous, but it is important to determine what it is.
• Unexplained weight loss or loss of appetite can also signal underlying disease.
• Other warning signs include unusual bleeding or discharge, sores that do not heal, persistent coughing, difficulty breathing, or changes in bathroom habits.
• A sudden drop in energy, reluctance to exercise, or unexplained pain may also indicate something deeper is happening.

It is important to note that canine cancers have latency periods of up to several years. What this means is that from the time that cells start becoming cancerous to when they become clinical symptoms may be several years. One study pointed out that “These doubling times would correspond to latency periods of 1 to 3 years …. However, these estimates are likely conservative since cancer is not typically diagnosed as soon as it reaches the threshold of clinical detection; in dogs, cancers are often
diagnosed, or present for treatment, in the range of 2.5 to 10 cm (containing 10 billion to 500 billion cells), corresponding to latency periods upwards of 5 years.”³

The key point is simple: early evaluation matters. “A prudent recommendation would be to start screening for cancer 2 years prior to the median age at diagnosis. In the current study, the median age at diagnosis was close to 9 years (8.8 years), supporting a recommended screening age of 7 years for all dogs. For dogs belonging to breeds with an earlier median age at cancer diagnosis (6 to 7 years), screening should begin as early as 4 years of age.”³

Many cancers are easier to treat when discovered earlier.

How Do Dogs Get Cancer?

Cancer develops when cells accumulate genetic damage that allows them to grow uncontrollably.

In dogs this process can be influenced by a variety of factors.

• Age is one of the strongest risk factors. As dogs live longer their cells accumulate more DNA damage over time.
• Genetics also plays a major role. Certain breeds appear to have a higher risk for specific cancers due to inherited mutations.
• Environmental exposures may also contribute. Chronic exposure to cigarette smoke, pesticides, herbicides, plastics, and other chemicals may increase long-term cancer risk.
• Some infections have also been linked to tumor development in specific cases.

Despite these factors, the reality is that in many cases the exact cause of cancer remains unknown.

Most Common Cancer in Dogs?

The Veterinary Cancer Society lists out the most common dog cancers as “lymphoma (up to 24% of all new canine cancers are lymphoma); osteosarcoma (most common primary bone tumor which accounts for 85% of all skeletal tumors and are quite aggressive); mast cell tumors (most common skin tumors in dogs); oral melanomas in dogs (most commonly occur on the skin, in the mouth and on the toenails); hemangiosarcoma (malignant tumors derived from the cells lining blood); and transitional cell carcinoma in dogs (most common tumor type of the urinary system in dogs).”⁴

Lymphoma, which is one of the most frequently diagnosed cancers in dogs has been studied extensively. This is the name for a group of cancers that usually start from a type of white blood cell called lymphocytes. There are different types of lymphoma and are named based on the areas they affect e.g. multicentric lymphoma affecting peripheral lymph nodes. Canine lymphoma can cause swelling in glands behind knees, armpits, organs in the chest causing respiratory issues and coughing, gastrointestinal organs resulting in severe vomiting or diarrhea or even in other distinct organs. Without treatment, lymphoma may progress rapidly and survival is often measured in weeks.

Mast cell tumors represent another common cancer where outcomes vary dramatically depending on tumor grade and stage. Mast cell tumors in dogs occur in the skin or just underneath the skin. Low-grade mast cell tumors that are surgically removed early may never recur, allowing dogs to live normal lifespans. Higher-grade tumors can spread to lymph nodes or internal organs and require more aggressive treatment.

Osteosarcoma in dogs refer to an aggressive and painful form of bone cancer. These typically are seen in larger dogs although they can occur in any dog.

Hemangiosarcoma presents a much more difficult challenge. This cancer arises from cells lining blood vessels and frequently affects the spleen, heart, or liver. One of the reasons hemangiosarcoma is so dangerous is that tumors can grow silently until they rupture and cause internal bleeding. Even with surgery and chemotherapy, survival times are often measured in months rather than years.

Dog Breeds Most Commonly Associated With Cancer

Cancer risk is influenced not only by age and environment but also by genetics. Over decades of selective breeding, certain mutations have become more common within specific breeds.

Large and giant breeds appear to have particularly elevated cancer risk, although smaller breeds can also be affected. Below is not an exhaustive list but it will help explain some of the more common breed predispositions.

Dog Breed	Most Common Cancer Types Observed	Notes
Golden Retriever	Lymphoma, Hemangiosarcoma, Histiocytic sarcoma, Osteosarcoma, Mast Cell Tumors, Melanoma	One of the most studied breeds due to high cancer incidence.
Boxer	Mast Cell Tumors, Lymphoma, Mammary Tumors (intact or late spayed females)	Strong genetic predisposition to mast cell tumors
Flat-coated Retriever	Histiocytic Sarcoma	One of the highest breed-specific risks for this cancer type
Bernese Mountain Dog	Histiocytic Sarcoma	Hich incidence to rare but aggressive immune cell cancer
Bulldogs	Lymphomas	Overall lower cancer incidence “due to its short life-expectancy due to other health issues”5
Pugs	Mast Cell Tumors	Generally lower overall cancer burden but still mast cell risk
Rottweiler	Osteosarcoma, Lymphoma, Histiocytic sarcoma,	Bone cancer common in large breeds
German Shepherd	Hemangiosarcoma, Osteosarcoma, Mammary Tumors (intact or late spayed females)	Hemangiosarcoma often affects spleen or heart
Labrador Retriever	Lymphoma, Mast Cell Tumors	Similar cancer patterns to Goldens
Scottish Terrier	Bladder Cancer, Lymphoma, Melanoma	Transitional cell carcinoma more common

These patterns highlight the importance of regular veterinary screening, particularly for breeds known to have elevated cancer risk. On the other end of the spectrum are low incidence of cancer dogs like Shih Tzu, Dachshunds and Lhasa Apso.

Some researchers suggest earlier screening may be worth discussing for high-risk breeds with one study suggesting around 4 years old.

In terms of screening, you can ask your vet to take blood tests (to detect certain kinds of cancer) or urine tests for things related to the bladder or prostate. Some veterinarians may discuss newer screening tools for high-risk dogs, though availability, cost, and usefulness vary depending on breed and cancer type. e.g. despite some limitations, IDEXX has come up with a screening, which showed canine lymphoma up to 6-8 months before clinical symptoms.¹²

How is Cancer in Dogs Treated?

Each cancer and cancer patient is unique. Modern veterinary oncology primarily targets abnormal cell signaling, tumor growth pathways, and immune responses. Current veterinary treatment primarily focuses on surgery, chemotherapy, radiation, targeted therapies, and immunotherapy. Veterinary oncologists choose from a range of interventions depending on the tumor’s biological behavior, location, and stage.

Surgery is commonly used for localized solid tumors and involves removing the cancer with a margin of healthy tissue, acting either to cure the disease or palliatively relieve pain and bleeding.

Chemotherapy is used for systemic cancers like lymphoma and targets rapidly dividing cells. In veterinary medicine, treatment is designed to prioritize quality of life and minimize side effects.

According to the US FDA, there are currently only 4 approved drugs to treat cancer in dogs. Here is their list of approved medication as of May 22, 2026.

• “Palladia (toceranib phosphate), to treat mast cell tumors, was approved in 2009;
• Stelfonta (tigilanol tiglate injection), to treat mast cell tumors, was approved in 2020;
• Tanovea (rabacfosadine for injection), to treat lymphoma, conditionally approved in 2016 and fully approved in 2021; and
• Laverdia (verdinexor tablets), to treat lymphoma, conditionally approved in 2021 and fully approved in 2025.”¹

For tumors in hard-to-reach locations like the brain or nasal cavity, radiation therapy is used to shrink tumors and reduce localized pain.

Cryotherapy offers a minimally invasive option for small, superficial skin tumors by using extreme cold to freeze, rupture, and eliminate malignant cells under local anesthesia. In some specialty settings, hyperthermia may be used alongside radiation or chemotherapy, though availability is limited.

Immunotherapy aims to stimulate the body’s internal defenses. However, for dogs the research is not complete and “this can make it harder to predict which dogs and which cancers are most likely to respond to immunotherapy.”⁷

When treatment is not possible, palliative care, which focuses on maintaining a pet’s comfort and quality is an important consideration. This includes pain management, dietary changes or other therapies also may be recommended to help your pet better respond. Once you have a diagnosis, your veterinarian can help you determine the best treatment option(s) for you and your pet, and will explain the risks and side effects associated with each. In some instances, your veterinarian may refer you to a board-certified veterinary oncologist or specialty clinic. 

What is the Treatment Success Rate for Canine Cancer?

Whether your pet will respond to treatment depends on the type and extent of the cancer, as well as the availability and effectiveness of therapy. Your pet’s age and health status also come into play, as some health conditions can limit treatment options. 
When it comes to the cancer itself, two things can affect treatment success:

• Stage: How large the tumor is and how far it’s spread to other areas of the body
• Type: What the cancer is and how it behaves in terms of aggressiveness and response to treatment

Depending on the situation, euthanasia may need to be considered, especially when the type or stage of cancer makes successful treatment unlikely or the pet’s quality of life is poor despite treatment. 

Is Canine Cancer Preventable?

Unfortunately, the cause of most cancers is unknown and many different factors may be involved, which makes prevention difficult.

Despite that, here are the few things we know about prevention from an environmental perspective:

1. Spaying eliminates the risk of ovarian cancer in female dogs and cats and reduces their risk of mammary cancer, especially when performed before the first heat cycle. For males, neutering eliminates the risk of testicular cancer. 
   • On the other hand, spaying and neutering may increase the risk of certain other types of cancers.
2. Minimizing secondhand smoke (by smoking outside away from pets) and thirdhand smoke (by airing house and laundering regularly) reduce the risk of cancer for pets. Secondhand smoke is defined as smoke from tobacco or marijuana inhaled by the dog or cat while thirdhand smoke is defined as smoke particles that left on clothing, fur or furniture for example. These can linger for a long time and be ingested or breathed in continuously. The National Cancer Institute has identified 7000 chemicals from secondhand smoke with “At least 69 of these chemicals are known to cause cancer, including arsenic, benzene, beryllium, chromium, and formaldehyde.”⁶ A study showed that smoke exposure increases the risk for pet nasal cancer while another one showed an increased risk for cat lymphoma and also lung cancer.
3. Minimizing exposure to pesticides and herbicides may may be associated with reduced cancer risk in pets. A peer-reviewed study associated exposure to lawn herbicides with increased rates of canine bladder cancer (transitional cell carcinoma), particularly in genetically predisposed breeds such as Scottish Terriers. One often-overlooked source of exposure is flea, tick, and mosquito “medications,” which are technically pesticides applied directly onto a pet’s skin or absorbed systemically. While these products may sometimes be necessary depending on region and lifestyle, reducing unnecessary exposure and using lower-toxicity prevention strategies where possible may be beneficial.
4. Choosing lower-to-no VOC products and flame retardants might be associated with reduced cancer risk in pets. Volatile Organic Compounds (VOCs) found in household products, synthetic fabrics, foams, paints, and low-quality pet beds may contribute to long-term toxic burden in pets. Dogs and cats spend much of their time close to flooring, fabrics, and treated surfaces where VOC concentrations can accumulate. An often-overlooked source of benzene VOC are aerosols and plug-in scent diffusers. Some VOCs such as benzene and formaldehyde are recognized human carcinogens.
5. Atopica, Apoquel, Steroids: While these medications are highly effective at suppressing severe allergies and inflammation, because they modulate the immune response, it is always wise to discuss long-term immune health and surveillance strategies with your vet if concerned about cancer.

Best Diets for Dogs With Cancer Based on Current Research

Nutrition cannot cure cancer, but diet can influence the biological environment in which cancer develops as well as maintaining weight for the cancer patient. For many dog owners, one of the first questions after diagnosis is whether diet or supplements could help support their dog’s health during treatment.

Diets That Limit Rapid Glucose Spikes

Many cancer cells demonstrate altered glucose metabolism, a phenomenon commonly associated with the Warburg effect. Because of this, some human nutritionists focus on dietary patterns that avoid large blood sugar spikes and instead emphasize protein, healthy fats, and slower-digesting carbohydrate sources.

However, it is important to note that subsequent studies on cancer cell metabolism have shown that these cells have flexibility to use carbohydrates, fat and protein depending on the environment they find themselves in. As such, utilizing diets have to be taken hand in hand with other treatments. Diets are useful in keeping the cancer patient at a healthy weight to endure treatments.

Ketogenic Nutritional Strategies

One of the most widely discussed experimental nutritional approaches for cancer is the ketogenic diet. A ketogenic diet dramatically reduces carbohydrate intake while increasing fat consumption. Some researchers hypothesize that certain tumors may be less metabolically flexible in utilizing ketones compared with healthy tissues, though responses likely vary by cancer type.

Unfortunately, results are still being released from peer-reviewed studies. While early results have shown ketogenic diets have worked for dog seizures, it is not currently recommended as a cancer treatment strategy in veterinary oncology.

Raw Dog Food and Minimally Processed Diets

The rationale for raw dog food is that highly palatable, nutrient-dense foods may help maintain caloric intake, muscle mass, and overall nutritional status during illness. These diets must still be carefully formulated to ensure they remain nutritionally balanced.

At Moonlight, we help Vancouver dog owners navigate and find the right raw dog food or even gently cooked dog food that should support healthy weight during cancer.

Case Study Pasha: Nutritional support case example (non-clinical, supportive care only)

This is not a treatment for cancer and should not be interpreted as such.

We had a particular case with a dog we helped who was diagnosed with cancer and had lost all his weight and muscle mass. He could barely stand or go out for walks. He was switched from his kibble to a raw dog diet specifically BC’s Best Raw Dog Food in September 2021. This was palliative nutritional support intended to improve body condition and appetite, not cancer treatment.

It was further combined with CBD to manage pain. His appetite improved and over the next month to two, he regained his muscle mass and weight. However, in December 2021, we said goodbye to him as the cancer was not being treated.

Supplements Studied for Metabolic and Immune Support

Some veterinarians may recommend supplements aimed at supporting appetite, inflammation balance, immune function, or liver support during treatment. Examples sometimes discussed include medicinal mushrooms¹³, milk thistle¹⁴, quercetin¹⁵ and berberine¹⁶. Evidence varies depending on the supplement and cancer type, so these should never replace veterinary treatment. These are not cancer treatments and should only be used under veterinary supervision due to potential drug interactions.

DIET + EXERCISE: It has become increasingly appreciated that diet and exercise play a huge role during cancer treatment.

FAQ: Canine Cancer

Final Thoughts

A cancer diagnosis is one of the most difficult moments in a dog’s life and in the life of the people who love them. But it does not always mean immediate loss. Many dogs continue to enjoy meaningful time with their families after diagnosis.

Understanding the disease, exploring treatment options, and focusing on quality of life can help guide difficult decisions. In the end the goal for most families becomes simple:

More comfort.
More good days.
And as much time as possible with a beloved companion.

References

1. “My Dog Has Cancer: What Do I Need to Know?” U.S. Food and Drug Administration, U.S. Department of Health and Human Services
2. Adams, V. J., et al. “Methods and Mortality Results of a Health Survey of Purebred Dogs in the UK.” Journal of Small Animal Practice, vol. 51, no. 10, 2010, pp. 512–524. Wiley Online Library.
3. Rafalko, Jill M., et al. “Age at Cancer Diagnosis by Breed, Weight, Sex, and Cancer Type in a Cohort of over 3,000 Dogs: Determining the Optimal Age to Initiate Cancer Screening in Canine Patients.” bioRxiv,
4. Pet Owner Resources.” Veterinary Cancer Society
5. Dobson, Jane M. “Breed-Predispositions to Cancer in Pedigree Dogs.” ISRN Veterinary Science, vol. 2013, 2013, article 941275
6. “Secondhand Smoke and Cancer.” National Cancer Institute, U.S. Department of Health and Human Services
7. Immunotherapy for Cancer Treatment.” Cornell University College of Veterinary Medicine, Cornell University College of Veterinary Medicine
8. Cancer in Pets.” American Veterinary Medical Association, American Veterinary Medical Association,
9. Dhein, Elena, et al. “Incidence Rates of Canine Tumors in Switzerland.”
10. Beal, Angela. “Dog Breeds and Cancer: Which Dogs Have Increased Risk?” The Vetiverse, 3 Feb. 2023,
11. Liberti, Maria V., and Jason W. Locasale. “The Warburg Effect: How Does it Benefit Cancer Cells?” Trends in Biochemical Sciences,
12. IDEXX Laboratories. Cancer Screening for Dogs. IDEXX, (May 2026)
13. PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board. “Medicinal Mushrooms (PDQ®)–Patient Version.” National Cancer Institute, U.S. Department of Health and Human Services, 11 July 2024
14. DQ® Integrative, Alternative, and Complementary Therapies Editorial Board. “Milk Thistle (PDQ®)–Patient Version.” National Cancer Institute, U.S. Department of Health and Human Services
15. Vafadar, Asma, et al. “Quercetin and Cancer: New Insights into Its Therapeutic Effects on Ovarian Cancer Cells.” Cell & Bioscience,
16. Wang, Haoran, et al. “Metformin and Berberine, Two Versatile Drugs in Treatment of Common Metabolic Diseases.”