Pet Care

12 Types of Cancers in Dogs and Cats

12 Types of Cancers in Dogs and Cats

Unfortunately, one in five cats and one in four dogs will develop cancer over their lifetime. Fortunately, not all pet cancer diagnoses are a death sentence—especially if you have an arsenal of knowledge and proper care on your side.

That said, you may have a chance of treating—or even preventing—different types of cancer in dogs and cats, depending on the severity of the condition.

What Is Cancer in Pets?

Neoplasms? Carcinomas? Stage IV? Before we tackle the types of cancer in cats or dogs, it's helpful to know the ins and outs of cancer terminology:

Neoplasm – A neoplasm is the abnormal and uncontrolled growth of any new cells or tissues in the body. While not all neoplasms lead to cancer, all cancer starts with a neoplasm.

Tumor – Also called a "mass," a tumor is when a neoplasm becomes a detectable raised cell mass, often with a border. Some tumors are benign (free of cancer), while others are malignant (cancerous).

Metastasis – Once a tumor or neoplasm begins spreading to other tissues in the body, it is undergoing metastasis. Veterinarians and doctors will "grade" a cancer diagnosis based on its metastasis progress, usually ranging from Stage I to Stave V. The higher the stage, the more deadly cancer.

Carcinomas – A malignant tumor signals cancer in certain organs, glands, and skin.

Sarcomas – These malignant tumors signal cancer in supportive tissue, such as bones, fats, muscles, fascia, or blood.

Remission – The symptoms and spread of cancer can be treated through a process known as remission. A cancer patient can enter partial or full remission.

Common Types of Cancer in Dogs and Cats

With cancer, knowledge enables prevention. The earlier you catch any signs of cancer, the more likely you can save your sweet pet.

#1 Lymphoma

Lymphoma is the most common cancer in dogs and cats, making up 20% of all canine cancer cases and 30% of all tumors in cats. This cancer starts in the lymphatic system—a network of tissues and glands that circulate lymph through the body to support immunity. For both cats and dogs, lymphoma can fall under several categories:

Multicentric– This full-body condition is the most common type of lymphoma for dogs, usually appearing first as swollen lymph nodes. Cats don't usually develop multicentric lymphoma.

Alimentary – This gastrointestinal cancer is the most common form of lymphoma for cats and fairly common for dogs. Cancer Symptoms in dogs include vomiting, abdominal pain, a lack of eating, and diarrhea.

Mediastinal – Common in cats and rare in dogs, mediastinal lymphoma starts in the chest. This type of lymphoma comes with respiratory issues like difficulty breathing and fluid in the chest.

Extranodal – When lymphoma affects non-lymphatic organs, it's called extranodal. Pet Dogs rarely have extranodal lymphoma, but cats are susceptible to renal (or kidney) lymphoma.

If you have a Bernese Mountain Dog, boxer, bulldog, bullmastiff, or Scottish Terrier, your pup may have a higher likelihood of developing lymphoma. For cats, medical experts believe that exposure to the Feline Leukemia Virus (FIV) increases a cat's chances for lymphoma.

Luckily, lymphoma is a relatively treatable form of cancer. About 85% of dogs and 70% of cats who receive treatment options for lymphoma will go into remission.

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#2 Osteosarcoma (Bone Cancer)

Out of all types of bone cancer in dogs or cats, osteosarcoma is the most common. Since this aggressive bone cancer affects the long bones in limbs, large dog breeds like Irish wolfhounds and Rottweilers are more likely to get it. In both cats and dogs, osteosarcoma can look like this:

  • Swollen mass on the skull, jaw, or ribs
  • Seizures
  • Wobbly or weak gait
  • Breathing difficulties
  • Loss of appetite
  • Fatigue

Unfortunately for dogs, osteosarcoma is often quite severe and spreads rapidly. Amputation can remove an infected limb, but most female and male dogs diagnosed with osteosarcoma will pass away within two years. Cats are at a lower risk of dying from osteosarcoma since most cases do not spread throughout the body.

#3 Mast Cell Tumors (MCT)

Mast cells are a type of white blood cell. When cancerous, these cells can form hard-to-find tumors (or MCTs) underneath the skin. Rarely visceral MCTs can form inside organs, a more aggressive form of this cancer. Siamese cats and dog breeds like boxers, shar-peis, bull terriers, and bulldogs are more susceptible to MCTs.

If you find a bump on your pet's skin, don't panic—about 90% of MCTs on the skin are benign. However, it's important to get a veterinarian's eye on any new growth you find, especially if you notice symptoms like:

  • Nodules on the head, neck, or ears
  • Itching at the site of nodules
  • Weight loss
  • Vomiting
  • Fatigue
  • Black stools

#4 Mammary Cancer

As you can guess, mammary cancer (or breast cancer) affects the mammary glands. However, mammary cancer is not a girls-only club. While most mammary cancer cases are in female cats and dogs, males can still develop this condition.

Mammary cancer almost always appears as a lump on the chest area. Your pet is more susceptible to mammary cancer if they:

  • Are a poodle, dachshund, or spaniel
  • Were formerly obese or currently obese
  • Were never spayed
  • Were spayed after 2 years of age (for dogs) or 6 months of age (for cats)

For cats, mammary cancer is a particular threat. Breast cancer is the third most common cancer for cats, with about 90% of feline mammary tumors being malignant. Fortunately, surgery can safely remove most cancerous breast tumors.

Types of Cancer in Dogs

From Newfoundlands to chihuahuas, every dog breed has the possibility of developing cancer. The following cancer types are found in canines of all kinds:

Hemangiosarcoma (HSA) – Fast and deadly, hemangiosarcoma occurs when a malignant tumor develops in the cells that line blood, usually in the spleen, liver, heart, or skin. Sadly, this type of cancer is usually untreatable, often wreaking internal damage by the time it's detected. The most susceptible breeds are golden retrievers, labradors, and German shepherds.

Melanoma – Melanoma affects the pigment cells in the body called melanocytes. In dogs, melanoma is most common in the mouth (a.k.a., oral melanoma), presenting as a darkly colored skin growth or tumors. Chow chows, miniature schnauzers, standard schnauzers, and Scottish terriers are more likely to develop melanoma.

Transitional Cell Carcinoma (TCC) – An aggressive form of cancer, TCC is typically found in the bladder with symptoms like bloody urine, incontinence, or pain during urination. Immediately take your dog to the veterinarian if you notice these signs, particularly if you own breeds like a Scottish terrier, Shetland sheepdog, or West Highlands terrier.

Intestinal adenocarcinoma – This rare but deadly cancer starts in the gastrointestinal tract, with a higher likelihood in older dogs over 9 years of age. Symptoms include weight loss, vomiting, diarrhea, and stomach swelling. Unfortunately, most pet dogs do not live beyond two years after a diagnosis.

Types of Cancer in Cats

Great news for cat owners—cancer is far less common in cats than in dogs. The less great news? When cats develop cancer, it's usually more aggressive. To protect your kitten's health, ask your veterinarian about these feline-affiliated forms of cancer:

Oral squamous cell carcinoma (SCC) – This skin cancer is the most common form of oral tumor in cats. Besides a noticeable lump, the first signs of oral SCC are usually drooling, oral bleeding, difficulty eating, or a bad smell from the mouth. To prevent cancer this condition, veterinarian experts recommend avoiding flea collars and exposure to carcinogens (like tobacco smoke).

Feline Injection Site Fibrosarcoma (FISS) – Fibrosarcomas can start in a variety of tissues, from muscles to bones. However, cats have a higher likelihood of developing fibrosarcomas at an injection site, known as FISS. While FISS only affects 0.01% of cats, it's still important to inspect any bumps that arise around injection sites.

Meningiomas – The most common type of brain tumors in cats, meningiomas affect male cats more than females. Typical symptoms include seizures, difficulty walking, and mental slowness. Radiation therapy is a treatment option, but most meningiomas have grown deadly by the time of detection.

Liver cancer – Older male cats are at the highest risk for liver tumors. This rare condition causes vomiting, nausea, diarrhea, pale gums, and jaundice. Luckily, the liver can be partially removed, so catching this cancer early could save your cat.

Prevent and Treat Pet Cancer with Papaya

Cancer is never a fun subject for any dog owner, whether for your furry pals or human friends. However, canine and feline cancer is far too common—and treatable—to ignore as a pet owner. With this guide, we hope you feel more prepared to prevent, identify, or treat any cancerous conditions in your pooch or kitten.

Found a suspicious lump on their skin? At Papaya Pet Veterinary Care, we are ready to help. Our care is designed to prioritize your pet's physical and mental health through a Fear Free philosophy. By creating a safe and soothing environment, your dog, whether a golden retriever or frenchie, or feline friend can feel just as excited when they hear the word "veterinarian" as they do "treat!"

No matter your concerns, we're here to provide solutions—give your pet the love they deserve by making an appointment at our animal clinic today. For more answers, head to our resource center to learn about everything from teeth cleaning, what causes cancer in cats, preventing cancer in dogs, to pet health records.


  1. American Animal Hospital Association. Is my dog at risk for cancer? our animal clinic today. Faha/canine-cancer/
  2. ASPCA. Understanding Lymphoma in Cats.
  3. BluePearl Pet Hospital. Canine Lymphoma.
  4. Colorado State University. Common Cancers In Cats.
  5. Country Living. These 27 larger dog breeds are more at risk of bone cancer, new study says.
  6. Long Island Veterinary Specialists. Canine Gastrointestinal Adenocarcinoma.
  7. Metairie Small Animal Hospital. Types of Feline Cancer and Their Most Common Symptoms.
  8. MetLife Pet Insurance. 7 Most Common Cancers in Dogs.
  9. Nationwide. Most Common Types of Pet Cancer.
  10. PetlifeSA. Types Of Rare Cancers In Cats.
  11. The Spruce Pets. 7 Types of Dog Cancer and Their Severity.
  12. UF Health College of Veterinary Medicine. Lung Tumors in Dogs.
  13. VCA Animal Hospital. Lymphoma in Cats.


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