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An owner pets their dog.

The essentials

  • Many factors contribute to a dog’s chance of developing cancer — Some are easier to control than others.
  • Different cancers display different symptoms in dogs —There are a few common problems you can look out for.
  • Take steps to decrease the likelihood of your dog getting cancer — Many of these are easy to do and may even improve your quality of life, too.

Causes of cancer in dogs

Cancer is a reality for humans and pets alike. Unfortunately, your best pal can get cancer, and it has the potential to be deadly. Cancer is the leading cause of death in dogs ages 10 and up. Causes of canine cancer include genetics, environmental factors, viruses, and hormones.


Some dog breeds inherit genetic traits that make them more likely to develop cancer. For instance, Scottish terriers are up to 20 times more likely to develop bladder cancer than other breeds. Poodles, golden retrievers, and Australian shepherds are more at risk of cancer of the lymph nodes. Boxers tend to be prone to mast cell tumors, a type of skin cancer.

Researchers are learning to identify genetic markers for these cancers. Genetic markers help breeders work toward eliminating these inherited traits from their lines. This means we should see fewer incidences of inherited cancers in future generations.

Environmental factors

A dog’s environment impacts its chances of developing cancer and what type. If someone in your household smokes, your dog is at an increased risk of tumors in the lungs and nose, particularly for long-nosed breeds like the Afghan hound. Second-hand smoke isn’t the only environmental factor that affects your dog’s health. Exposure to pesticides and herbicides raises a dog’s risk of cancer. The risk also increases with canine obesity. Pups that spend a lot of time in the sun are at an increased risk of developing skin cancers. This is especially true if they’re fair-skinned.

Of course, certain environmental factors are outside of our control. One study compared cancer rates in dogs living near waste management facilities. It found a connection between the dogs’ proximity to the facilities and an increased risk of lymphoma. And dogs, like humans, are susceptible to allergens and pollutants in the air and water.


Certain viruses increase a dog’s risk of developing cancer. A trip to the dog park or a busy boarding facility may find Fido catching the contagious papillomavirus, which can lead to oral skin tumors. These tumors tend to be low-risk and resolve on their own.


Sex hormones can play a role in the development of cancer as well. For this reason, there are conflicting opinions in the veterinary medicine world about when to spay and neuter dogs.

Studies show that female dogs that go into heat once or twice before being spayed are at an increased risk of developing cancer of the mammary glands. But studies also indicate that the earlier a dog is spayed or neutered the more likely it is to develop bone sarcoma, lymphoma, and mast cell tumors. At least one study found that one in four neutered or spayed dogs were more likely to develop osteosarcoma than dogs left intact. Breeds like Labrador retrievers are also more susceptible to hormone-related cancers.


Advances in veterinary science have extended our dogs’ lives. We all want our pets to live longer, but a longer life increases a dog’s risk of contracting cancer during its lifetime. Recent research suggests that evolutionary biology has a major role to play here. Simply put, dogs are living longer as pets than their wild ancestors. Because of this, they’re exposed to more cancer-causing factors than in the past. This increase in lifespan has outpaced their evolutionary ability to develop cancer-fighting traits.

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While age-related cancers can be difficult to prevent, there are steps you can take to reduce your dog’s risk. The omega-3 fatty acid docosahexaenoic acid (DHA) is essential in helping prevent chronic health issues, including certain cancers.

Functional foods such as ZipZyme™ Omega are a more highly bioavailable source of DHA — ZipZyme™ is sourced from natural ocean algae which contain special enzymes that allow it to produce DHA internally. It’s the only omega-3 DHA product that stops the accumulation of unhealthy saturated fats that contribute to certain cancers because when trying to improve metabolic function in pets and in people, it all comes down to “we are what we eat.”

Common types of cancer in dogs

Certain cancers are more common than others in dogs. Learning to recognize signs and symptoms of these cancers can increase the chances of early detection.

  • Hemangiosarcoma. This deadly cancer originates in the bone marrow and can spread to the heart and spleen. Hemangiosarcoma is generally found in larger breeds or older dogs.
  • Mast cell tumors. This cancer develops in the cells in the immune system. They react to inflammation and allergic reactions in a dog’s body. These are usually highly treatable with early detection.
  • Lymphoma. Cancer of the white blood cells. Lymphoma tends to be found in organs that play a role in the immune system like the lymph nodes, spleen, and bone marrow.
  • Osteosarcoma. An aggressive form of bone cancer that typically develops in the larger bones of the legs, but can also occur in the pelvis and even soft tissue. Osteosarcoma is more common in large-breed dogs.
  • Brain tumors. Tumors in the brain or the lining that surrounds the brain. Brain tumors can either be primary (develop in the brain) or secondary (cancers that have spread to the brain from other parts of the body). Most dogs that develop brain cancers are over the age of five.
  • Bladder cancer. A cancer in the interior and muscle layers of the bladder. This form of cancer is rarer than other cancers found in dogs, but it’s found most often in Scottish terriers.
  • Mammary carcinoma. Cancer of the breast tissue. This tends to be more common in certain breeds, including Chihuahuas, dachshunds, poodles, Yorkshire terriers, Cocker and Brittany spaniels, English setters, boxers, and Doberman pinschers.
  • Squamous cell carcinomas. Cancer of the skin’s epidermal, or outer layer often presents as a raised lump, on the nail beds, or in the mouth.
  • Melanoma. A tumor that develops in melanocytes, the body’s pigment-producing cells. Most commonly occurs in the mouth or between the toes.
  • Testicular. Cancer of the testicles in intact male dogs. Outlook is usually good, with cancer treatable via surgery.

How to know if your dog has cancer

Though every cancer presents differently, there are some common warning signs to watch for. These include:

  • Abnormal lumps and bumps that appear suddenly and grow at a rapid pace;
  • Loss of appetite and weight loss
  • Sores that don’t heal
  • Bleeding or discharge from any opening on the body
  • Difficulty eating, swallowing, or breathing
  • Difficulty walking, including limping and/or stiffness;
  • Difficulty with bathroom functions, including straining to pee or poop;
  • Abnormal vomiting or diarrhea
  • Foul odors, especially coming from the mouth, nose, or anus
  • Loss of interest in exercise or play

None of these symptoms on their own are a definitive sign of cancer. Because of this, it’s always best to keep up with your dog’s regular vet visits to get an expert opinion. There are cancer screening tests available from your veterinarian, including lab work, X-rays, and ultrasounds that can be performed yearly on senior dogs. There are also specific tests, such as the OncoK9 cancer test, that are designed to detect cancer in high-risk breeds.

Treatment for cancer in dogs

You may already be familiar with common cancer treatments for humans. Our pups often undergo similar treatments. Sometimes taking care of the cancer involves a combination of treatments. Your vet chooses these treatments based on the type and severity of the cancer and how quickly it spreads.

  • Chemotherapy. Chemotherapy can be delivered orally, in pill form, or through injection. Dogs get chemotherapy treatments in lower doses than humans. They can still experience similar side effects like nausea, digestive irritation, and a low white blood cell count.
  • Surgery. Surgery is the oldest cancer treatment, and often the most successful. Your pup may have a biopsy to diagnose the cancer. Later treatment might be a total removal of cancerous cells.
  • Radiation therapy. Radiation kills cancer cells by focusing a beam of intense energy on the cancerous area. Radiation is often prescribed in combination with other treatments.
  • Immunotherapy. This treatment uses your dog’s own immune system to destroy cancer cells. Though not all patients respond to immunotherapy, for those that do, it can be a gentler and more targeted treatment option. Canine immunotherapy is still in its earlier stages. It tends to work better after other treatments, such as chemo and radiation, have decreased the amount of cancer in a dog’s body.
  • Holistic or herbal therapy. Holistic therapy is an approach that takes into account not just the cancer symptoms but the dog’s lifestyle. It uses natural remedies like natural anti-inflammatories and antioxidants to boost the dog’s immune system and help it fight cancer.

How to decrease the risk of cancer in dogs

There are steps you can take to reduce the risk of your dog developing cancer in the first place, and they might begin before you even become a pet parent.

Breeder selection

Sometimes the best way to fight canine cancer is to consider a puppy’s health before you ever add one to your family. Selecting a reputable breeder is an important step in this process.

Look for a breeder with a good word-of-mouth reputation among dog owners, a strong working relationship with a vet, and extensive knowledge of their chosen breed. A reputable breeder should welcome your questions about health conditions and temperament and allow you to visit their breeding facilities. The American Kennel Club is a good place to start your search.

Spaying and neutering

During your puppy’s first appointments, speak to your vet about when they recommend spaying or neutering your new pet. Your vet should consider your dog’s breed, age, and health. You may also wish to spay or neuter an older adopted dog to prevent future health complications.

Proper nutrition

Though no one food or supplement can completely prevent cancer, proper nutrition is key to boosting your pet’s health and immune system. Keep an eye on portion size, frequency of meals, and nutritional value of the food you give to your dog. Obesity significantly shortens a dog’s life span by making it susceptible to several health conditions.

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A healthy metabolism from an early age may ward off serious health conditions such as obesity and diabetes. Among ZipZyme™ Omega’s many DHA benefits, including heart and brain development, is that the enzymes it contains work to convert sugar to healthy fats, keeping the metabolism balanced and dogs healthy and happy. ZipZyme™ Omega can supercharge vitality — it comes in one-teaspoon servings which can be mixed into your dog’s favorite wet or dry food each day.

Healthy lifestyle choices

Lifestyle is just as important as diet when it comes to keeping your pooch healthy. Regular exercise can help prevent pet obesity, not to mention keep your pup, and you, entertained. And don’t forget to engage that brain! Nosework, puzzles, or a good whiff of every scent on your walk helps keep your pup sharp. This, in turn, keeps them active.

Reduced exposure to harmful substances

Of course, we all want to keep harmful substances away from our pets. But reducing cancer risk is another reason to be extra cautious about your pooch’s exposure to cigarette smoke, pesticides, and caustic household cleaners. Always read the labels, and choose gentler or natural formulas free of carcinogens.

Frequently asked questions

What foods cause cancer in dogs?

No individual foods have been identified as cancer-causing in dogs. But, toxins produced by mold that can grow in commercial dog foods, called mycotoxins, can be cancer-causing. Some dog owners choose alternate or homemade diets to avoid this.

Does stress cause cancer in dogs?

Several studies have suggested that stress does play a role in causing cancer in dogs. The medical community continues to explore whether stress causes cancer in humans. Hopefully, as our knowledge of canine cancer develops, we can learn more about how it’s linked to stress.