Lymphoma in Pets

Lymphoma is a very common cancer in dogs and cats. It is caused by uncontrolled growth of lymphocytes, a type of white blood cell. Since these blood cells can easily travel through the blood or lymphatic system, it is very common for this cancer to affect multiple sites in the body. While it can affect any dog or cat, it is more common in certain breeds of dogs (such as Golden Retrievers and Boxers) and in cats that carry the feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV).

Signs and Symptoms 

• Dogs
  • Dogs with lymphoma most commonly present with enlarged external lymph nodes (usually the lymph nodes under the chin, in front of the shoulders, and behind the knees).  
  • They may not show any other symptoms, but sometimes they have general signs of illness such as:
    • Low energy 
    • Low appetite
    • Increases in thirst and urination are also occasionally seen 
• Cats
  • Lymphoma in cats most often affects the gastrointestinal tract, so cats with lymphoma often have gastrointestinal symptoms such as:  
    • Vomiting 
    • Diarrhea
    • Weight loss
    • Loss of appetite

The Diagnosis Process  

The diagnosis of lymphoma requires additional tests done by a veterinarian, most commonly by obtaining a sample of the affected organ or tissue and sending it to a pathologist for review. 

• In pets with enlarged lymph nodes, the diagnosis can often be confirmed with a small fine needle aspirate, in which a small needle (no larger than the kind used to give a vaccine) is inserted into the enlarged lymph node.  
• For animals that have lymphoma in their internal organs, usually imaging tests (such as ultrasound) and even surgical biopsies under general anesthesia may be needed to confirm the diagnosis. 

Treatment Options 

Since lymphoma is a systemic disease, it requires systemic treatment: chemotherapy, usually combined with steroids.  

• Chemotherapy 
  • Fortunately, chemotherapy doesn’t typically have the same negative effect on pets as it does on people. You can learn more about chemotherapy and the quality of life for pets here. 
  • Many pets with lymphoma can go into remission with chemotherapy, which means all detectable signs and symptoms of their cancer will disappear for a period of time. Most forms of lymphoma in pets are not curable, however, and relapse is common. Even though lymphoma rarely can be cured permanently, pets can live longer (and happier!) lives with chemotherapy. 
  • There are several different chemotherapy protocols used to treat lymphoma, depending on: 
    • The type of lymphoma
    • The pet parent’s goals and resources 
    • How well pets tolerate frequent vet visits 
  • Chemotherapy protocols may range from weekly treatments given for several months to a treatment every 2-3 weeks. The oncologist reviews these options in detail at the initial consultation. No treatment plan is ever set in stone, and we can change plans at any time if pet parents change their minds. 
• Steroids
  • Steroids are often combined with chemotherapy, but pet parents who choose not to pursue chemotherapy may opt to use steroids alone, typically prednisone or prednisolone. These are great palliative drugs for lymphoma, and even steroids alone can make pets with lymphoma feel better for a period of time.
  • Steroids may only help for a couple of months, but this gives pet parents a little more time to say goodbye while their pet is feeling better.  

Prognosis & Expectations  

Prognosis for lymphoma depends on: 

• The specific type of lymphoma
• How the pet is feeling at diagnosis
• The treatment option pet parents pursue
• The location of the lymphoma in the body (in some cases) 

Prognosis for dogs with the most common form of lymphoma (affecting the lymph nodes) can range from 6-14 months with the most effective chemotherapy protocol. For cats with lymphoma affecting their gastrointestinal tract, the small cell lymphoma form has a prognosis of around 2 years with chemotherapy, while cats with large cell gastrointestinal lymphoma may only live a few months.

The goal of our Oncology Service is to provide every patient with the highest quality of life for as long as possible. We fully support pet parents in whatever lymphoma treatment option they choose, respecting their decisions about what is best for their pet’s well-being. 

Learn more about our Oncology Service here.  

More Reading:  

• Common Types of Cancer in Pets | Part I: Determining a Diagnosis
• Navigating a Pet’s Cancer Diagnosis: Part 1
• Debunking Pet Cancer Myths
• Early Detection of Cancer in Dogs and Cats: 5 Things Pet Owners Can Do
• Chemotherapy and Quality of Life in Dogs and Cats