Common Types of Cancer in Pets | Part I: Determining a Diagnosis

It can be frightening to face a cancer diagnosis with your pet. Hopefully, we can demystify cancer and tumors for pet parents and give them helpful information – because information is the best weapon against cancer.

In October of 2023, Dr. Keepman, one of our board-certified veterinary oncologists, joined us on Facebook Live to discuss common types of cancer in pets. You can watch the replay of the video or read a thorough summary below. 

Our Oncology Service sees all different types of breeds and ages of pets with cancer. Depending on the extent of the cancer, pet parents or a family veterinarian may notice signs that may appear overnight or over several weeks to months. Often, it’s these initial signs that prompt further testing:  

• Lump or bump 
  • An obvious mass somewhere on the skin 
  • A lump under the chin, in front of the shoulders, or behind the knees 
  • Enlarged lymph nodes 
• Low appetite
• Low energy levels 
• Lameness, limping, or not bearing weight on a certain limb (Common in bone tumors such as osteosarcoma) 

Steps to a Diagnosis 

Know that the above symptoms don’t necessarily mean your pet has cancer, but they do warrant a visit to your family veterinarian to determine the underlying cause – which may indicate cancer, an inflammatory condition, a soft tissue injury, or something else.  

Depending on changes you noticed and what your family veterinarian observes, your pet’s visit may include one or more of the following:  

• A Physical Exam 
  • During the physical exam, your family veterinarian will:
    • Feel your pet for any lumps and bumps around the body 
    • Feel lymph nodes 
    • Assess if there are any signs of pain at certain points of the body 
    • Look for abnormalities such as unnoted lumps or an internal bump vs. a lymph node  
• Fine Needle Aspiration 
  • Fine needle aspiration is a common, non-invasive test that involves poking a small needle into a mass to collect cells for a pathologist to review microscopically. Results are typically returned within a few days.  
  • It feels like a vaccine, so most pets don’t mind much and do not require sedation or anesthesia.  
• Bloodwork 
  • A basic bloodwork panel will look for abnormalities in your pet’s organ function, red blood cells, white blood cells, as well as liver and kidney values.  
  • The results may not necessarily provide a definitive diagnosis of cancer, but they help us get an overall picture of your pet’s health.  
• X-rays 
  • X-rays of an affected limb can help determine if there are abnormalities with the bone or soft tissue. 

When Should My Pet See a Veterinary Oncologist?   

Often, pets visit our Oncology Service after receiving a confirmed cancer diagnosis from their family veterinarian. Even if you know you won’t pursue chemotherapy or other treatments, our board-certified veterinary oncologists can provide a lot of valuable information, including: 

• More information on your pet’s specific type of cancer 
• Treatment or management options
• Prognosis
• Hospice care 

However, your pet doesn’t always need a definitive diagnosis prior to referral. Sometimes, additional testing, biopsies, or advanced imaging such as CT are needed to confirm the diagnosis, determine if the cancer has spread, and help determine the next steps in your pet’s care.    

Most Common Types of Cancer Diagnosed in Pets 

Once an exam and all testing, including biopsy and imaging results, are complete, your family veterinarian or oncologist will be able to diagnose your pet. There are many different types of cancer, but the most diagnosed cancers in pets include:   

• Lymphoma  
  • A cancer of a type of white blood cell 
• Mast cell tumors  
  • The most common skin tumor in dogs and one of the most common types of tumors in cats 
• Osteosarcoma  
  • A very common bone tumor we see – mostly in large and giant breed dogs 
  • Cats can be affected too, but less commonly 
• Soft tissue sarcomas  
  • A tumor of the skin or the subcutaneous tissue  
  • Can be found on internal organs, too  
• Oral tumors  
  • Common in both dogs & cats  
    • Oral melanomas in dogs 
    • Squamous cell carcinomas in cats 

After a diagnosis is determined, the next step is to establish a plan with your family veterinarian or oncologist. Continue to Part II to learn more about how to make those difficult decisions when it comes to treatment options and determining when it’s time to consider euthanasia.