Lymphoma (Lymphosarcoma) in Dogs and Cats

What is lymphoma (lymphosarcoma)?

Lymphoma is one of the most common cancers seen in dogs and cats, and may account from anywhere between 10 and 20% of all cancers seen in pets. Pet lymphoma originates in cells known as lymphocytes, which are a specific type of white blood cell of the immune system. Lymph nodes, spleen and bone marrow are commonly affected. Lymphoma can also occur in any organ in your pet's body that contains lymphocytes, including the digestive tract, chest cavity, eyes, central nervous system, nasal cavity, bladder, heart, and even the skin. Lymphoma can be classified into several possible categories depending on the predominant location of the cancer.

Key facts about lymphoma in dogs and cats

• Lymphoma is one of the most common cancers seen in dogs and cats.
• Symptoms of lymphoma mimic many other common diseases, so a full veterinary examination is necessary in any chronically ill pet.
• Lymph node aspirate or biopsy is necessary to make a definitive diagnosis of lymphoma.
• Lymphoma in dogs and cats is most successfully treated using a combination of chemotherapeutic drugs.
• If treated early, many pets can live comfortably for 6-12 months, with some pets living two years or more.

Causes of lymphoma in dogs and cats
Even though lymphoma cancer is quite common in dogs and cats, there are no proven specific causes found in most cases. Although genetic predisposition is suspected, many holistic veterinarians believe that environmental factors, including overvaccination, toxic pet foods, and chronic reactions to chemical pesticides may play a role in some pets with lymphoma. Prolonged use of immune-suppressive medications may also lead to immune system breakdown and cancer development.

Pets most at risk for lymphoma
In cats, lymphoma can occur in both young and older pets. Cats under one year of age that test positive for feline leukemia or feline immunodeficiency virus may develop cancer of the thymus and lymph nodes in the chest cavity. This type of lymphoma is known as mediastinal lymphoma. Older cats may typically develop cancer in a wider variety of areas including the peripheral (external) lymph nodes, digestive tract, kidneys, eyes, skin, nasal cavity, and central nervous system. There does not seem to be any specific breed predilections in cats. In dogs, certain breeds may be more prone to lymphoma, including Airedales, Bulldogs, Golden Retrievers, Boxers, Basset Hounds, Schnauzers, Saint Bernards, and Scottish Terriers. Middle aged to older dogs are more likely to be affected.