Canine & Feline Cancer Awareness, Diagnosis, and Treatment

Has your dog or cat been diagnosed with, treated for, or succumbed to cancer?

For owners, learning of a canine or feline companion’s cancer diagnosis is one of the worst conversations that can be had with a veterinarian.

Along with conveying the cancer diagnosis to my clients I‘ve also diagnosed and treated cancer in my own dog Cardiff.  I’m well aware of the many concerns faced by owners caring for a beloved pet during cancer treatment, but seeing my own canine undergo the process was a life-changing experience that gave me hope for my patients.

What is cancer?

Cancer occurs in cells having abnormalities in their DNA (genetic material) that inhibits cellular division.  Non-cancerous cells have genetic mechanisms that control their ability to divide and can engineer their own death if cellular health is too forgone to permit appropriate function.  Cancer cells continue to replicate and cannot turn off their growth.  As a result, tumors (clusters of cancers cells) form that cause damage to normal body structures at the sites where they form and sometimes in other body systems.

Cancer has two primary categories; benign and malignant.  Benign cancers still create concern for overall health, but they generally have a low likelihood of developing quickly and metastasizing (spreading to other parts of the body) and have a better outcome.  Malignant cancers have a high likelihood of growing rapidly and metastasizing from a primary site and typically are more life threatening.

There is no single known cause of cancer, but research has proven that genetics, environmental and toxin exposure (sun, fertilizer, pet foods and treats, etc.), lifestyle choices (diet, lack of activity, obesity), disorders of chronic inflammation, and other factors all play a role.

The diagnosis of cancer is typically a life-altering one for both pets and the people who care for themOwners are faced with emotional, financial, and logistical burdens that ultimately complicate the treatment equation.

Cancer statistics aren’t favorable for our animal companions.  According to

  • Cancer contributes to nearly 50% of all disease-related pet deaths each year.
  • Dogs get cancer at nearly the same rate as humans.
  • Approximately 1 in 4 dogs develops a tumor during its lifetime.

Can any canine or feline be affected by cancer?

Yes, any pet can be affected by cancer regardless of life stage.  Cancer mostly affects adult and senior pets, but benign and malignant tumors can also develop in puppies and kittens.

Purebred canines and felines are generally more commonly affected by cancer than mixed breeds, but such finding may be partially due to it being simpler to track veterinary health information pertaining to pure breeds.  Yet, mutts and Domestic Short Haired (DSH, a term for short-haired cats of mixed breeding) can be diagnosed with the same cancers as their purebred counterparts.

With dogs, there is often a correlation between certain cancers and canine body size.  For example, malignant bone tumors like osteosarcoma and malignant blood vessel tumors like hemangiosarcoma are diagnosed more frequently in large and giant-sized mixed and pure-breeds than in their smaller counterparts.


What are clinical signs my dog or cat may have cancer?

There are many clinical signs of cancer in pets, which may be subtle to obvious.  The Veterinary Cancer Group (VCG) has a team of veterinary oncologists capable of providing cutting-edge cancer treatments for pets and help educate owners on early illness recognition via their 10 Warning Signs of Cancer in Dogs & Cats:

  1. Persistent change in appetite and/or water intake
  2. A lump that is enlarging, changing, or waxing and waning in size
  3. Progressive weight loss or weight gain
  4. Non-healing sore or infection, such as persistent nail bed infection
  5. Abnormal odor
  6. Persistent or recurring lameness
  7. Chronic vomiting or diarrhea
  8. Persistent or recurring cough
  9. Unexplained bleeding or discharge
  10. Difficulty swallowing, breathing, urinating, or defecating

Although any lump or bump you feel or see on your pet can raise concern for cancer, a mass-like lesion that you discover may or may not actually be a benign or malignant tumor.  Cysts, hives (urticaria), hot spots, insect bites, scar tissue, and other skin disorders can potentially mimic cancer.

Due to the similar appearances of cancerous and non-cancerous mass-like lesions, it’s crucial that any concerns recognized by pet owners are immediately addressed by their veterinarian.

How can cancer be diagnosed in canines & felines?

Besides a suspicion of cancer based on clinical signs, there are many ways it can be diagnosed.  Some diagnostics create the suspicion of cancer while others may provide a definitive diagnosis.

Fine Needle Aspirate (FNA) for cytology – If a mass-like lesion is the size of a pea or larger, then performing FNA to attain a small sample of cells for cytology (microscopic evaluation) is merited.  FNA can be performed without sedation or anesthesia provided the pet is properly restrained.  FNA is a great starting point to determine if further diagnostic testing is needed.

Biopsy – Biopsy involves obtaining a larger piece of tissue than that obtained by FNA and has many advantages over cytology in that tissue layers can be microscopically visualized as they appear in the body.  Maintaining the normal cellular architecture of the sample can provide crucial insight when attaining a definitive diagnosis instead of just a clinical suspicion based on FNA/cytology.

Blood, urine, and fecal testing – Some cancers can cause alterations from the normal range in blood values pertaining to the kidneys, liver, electrolytes, calcium, glucose, red/white blood cells, platelets, thyroid glands, and more.  Cancer can also alter the normal characteristics of urine and feces.  As many cancer treatments (chemotherapy, etc.) can take their toll on normal body functions, it’s necessary to repeatedly perform diagnostics like blood testing.

Radiographs (X-rays) – Radiographs create a static image that permits doctors to form a 3D image to yield information about pet health.  Radiographs are very useful in establishing the initial clinical suspicion of cancers of bone, lungs, and some soft tissue structures (liver, spleen, muscle, etc.).

Ultrasound – Whereas radiographs create a static image, ultrasound produces a real-time, moving picture of your pet’s internal organs.  Crucial information about your pet’s abdominal organs, heart, and blood vessels is better attained via ultrasound than x-rays.  Yet, dense structures like bones, joints, lungs, and others can’t be readily penetrated by ultrasound waves and are better evaluated via radiographs.

CT scan and MRI –  When radiographs and ultrasound don’t create a thorough-enough picture of a pet’s internal organs, other imaging techniques like Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) can service the need.

CT scans are primarily used to look inside cavities like the chest or abdomen to evaluate soft tissue structures like the lungs, spleen, liver, kidneys, or mass-like lesions taking up space inside the nasal cavities.    According to Southern California Veterinary Imaging (SCVI), a “recent study in the Journal of College of Veterinary Radiology found that CT scans are five to six times more sensitive than radiography in detecting soft tissue nodules (metastasis) within the lungs.”  MRI is the preferred imaging technique to look at structures like the brain, spinal cord, nerves, and intervertebral discs.

Unlike radiographs and ultrasounds, MRI and CT scans require pets to be fully anesthetized to prevent movement that negatively affects the ability to capture an image.

Nuclear Imaging – For some cancers and other ailments, more advanced tests are needed to detect abnormalities when radiographs, ultrasound, MRI, or CT scan can’t fully suffice a pet’s diagnostic needs.

Nuclear imaging uses radioactive isotopes injected into blood vessels which move to areas of tissue having increased cellular activity like cancer.  One application of nuclear imaging used in cancer diagnosis is a bone scan.  Malignant bone cancers like osteosarcoma rapidly grow and damage normal structures.  SCVI reports that “30-50% of bone loss must be present in order for the changes to be visible on x-rays,” so the bone scan can help veterinarians better localize concerning sites to facilitate bone biopsy or body-part amputation and biopsy to confirm the diagnosis suspected from radiographs.

Diagnosing the cancer early on allows the disease to be treated more quickly and spares the patient severe pain and potential metastasis to other sites.

What cancer treatment options exist for dogs and cats?

Despite the concerning statistics about cancer frequency in pets, the positive news is that pets are surviving longer and overcoming cancer due to the numerous therapeutic options available.

Cancer treatment has evolved to the point that your pet’s disease may be resolved or well-managed via:

Surgery – “A chance to cut is a chance to cure” is one of my favorite phrases in veterinary medicine.  A tumor can be surgically removed from the body and potentially leave the pet in remission (having no detectable signs of disease).

Alternatively, tumors can be surgically debulked (partially removed) so that the number of cancer cells capable of causing illness or metastasizing is significantly reduced.  The likelihood of curing cancer via surgery is higher when wide margins of normal tissue around the tumor can be attained to minimize the potential for cancer cells to remain in the body.

Radiation – Some tumors cannot be surgically removed or cancer cells can be left behind post-surgery if wide margins are not achieved.  That’s where radiation serves to kill cancer cells, shrink tumors, and improve a pet’s comfort and quality of life.  Depending on the number of radiation treatments needed your pet may show mild to moderate skin side effects (inflammation, infection, pain, etc.).  General anesthesia is required for each radiation treatment, but anesthetic times are short and pets generally wake up quickly.

Chemotherapy – A variety of chemicals capable of killing cancer cells are available to be administrated as an injection (intravenous or intramuscular) or orally.  Fortunately for pets, chemotherapy is often used in smaller doses than for humans and thereby can produce fewer side effects.

As the degree to which cancer is present in each pet’s body is different, chemotherapy protocols must be individually tailored for each patient.  A pet’s response to chemotherapy and the development of side effects (lethargy, digestive tract upset, etc.) must be closely monitored by both the overseeing veterinarian and owner.

Nutrition – The body is best able to participate in the cancer battle when all parts are optimally working, so nutrition is a crucial component of cancer treatment.  For all pet life stages, but especially during treatment for cancer, a whole-food diet providing an appropriate balance and diverse variety of fresh, moist meat, vegetables, fruits, and grains has higher bioavailability (better absorption and utilization) than processed diets like kibble dry food.  Such is why one of my top pet foods and treat recommendations is The Honest Kitchen.

There’s no diet appropriate for all pets, so I advise feeding cooked meat diets that are commercially available or home prepared depending on the patient’s needs and the owner’s desire for convenience in the food-preparation process.  Raw meat diets or those not undergoing some degree of heating can increase the potential that pathogenic bacteria that otherwise would be killed during the cooking process can sicken your pet.

Complementary and Alternative Medicine (CAM) – CAM is the primary focus of my veterinary approach to treating cancer patients.  Treatments I advocate include digestive tract and immune system supporting and naturally anti-inflammatory nutraceuticals (supplements, like pre- and probiotics, ginger, turmeric, omega fatty acids, etc.), herbal products, and acupressure/massage and acupuncture.  Chinese medicine food energy therapy also can aid cancer patients, as nutrients having cooling energetic properties help clear heat caused by cancer cell division and tissue inflammation.

As cancer is a multifaceted disease that’s very challenging to treat I already recommend owners pursue a consultation with veterinary oncologist who exclusively dedicates their practice to managing such a life-changing disease.   Your regular veterinarian can refer you to a veterinary oncologist or one can be found by visiting the American College of Veterinary Internal Medicine (ACVIM).

Feel free to share your perspective on pet cancer treatment in the Comments section.

Interested in seeing the impact of diet on pets with cancer?  Read through our True Stories here.

Meet the Author: Patrick Mahaney

Dr. Patrick Mahaney VMD, CVA, CVJ is a veterinarian and certified veterinary acupuncturist providing services to Los Angeles-based clients both on a house call and in-clinic basis. Dr. Mahaney’s unique approach integrating eastern and western medical perspectives has evolved into a concierge house call practice, California Pet Acupuncture and Wellness (CPAW), Inc. Additionally, Dr. Mahaney offers holistic treatment for canine and feline cancer patients at the Veterinary Cancer Group (Culver City, CA).

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