by ​Association of Exotic Mammal Veterinarians:

Lymphosarcoma (also known as lymphoma) is a cancer of the lymphatic system.  The lymphatic system is responsible for filtering debris from the death of cells and bacteria, and production of antibodies to help fight disease.  Tumors that affect the lymphatic system can prevent normal function and can affect multiple organ systems.  Lymphosarcoma is the most common hematopoietic cancer in the ferret and in other animal species as well.

What causes lymphosarcoma?

Exactly what transforms an apparently healthy cell into a cancerous cell is unknown.  Many studies are being done in the field of cancer research to determine this.  Although unproven, some researchers believe a virus may cause this disease in ferrets.

What are the clinical signs?

Clinical signs of the disease vary depending on the organ systems involved and the extent of the disease.   Ferrets often appear normal and show no outward physical signs.  There are two general forms of lymphosarcoma in the ferret.  One form primarily affects young ferrets under 2 years of age – this is a rapidly progressive lymphoblastic form.  The other form of the disease affects older ferrets and is a more chronic lymphocytic disease.

The lymphoblastic form affecting young ferrets causes infiltration of cancer cells into various abdominal organs such as the spleen and liver and thymus. Because this form usually doesn’t cause obvious enlargement of the lymph nodes, it can be easily missed. Clinical signs depend on which organs are involved.  A common presentation is breathing difficulty due to enlargement of the thymus gland in the chest, which may be mistaken for pneumonia or heart disease.  Less commonly, the liver may be infiltrated resulting in jaundice (icterus).  Lymphoblastic lymphosarcoma should always be ruled out in any young ferret with any serious illness.

The lymphocytic form is the classic form and is usually seen in older ferrets. This form usually develops more slowly, and causes visible enlargement of peripheral lymph nodes. Internal lymph nodes can also be affected.  Late in the course of the disease, organs such as the liver, spleen, kidneys, gastrointestinal tract and lungs are infiltrated, resulting in organ failure and death.  This disease is often insidious in nature and the ferret may not appear sick until later stages. Occasionally, a leukemic form of lymphosarcoma may be seen in the latter stages of either form.  In this form, the neoplastic lymphocytes circulate within the peripheral blood.

How is the disease diagnosed?

Lymphosarcoma can be a difficult to diagnose.  Definitive diagnosis requires interpretation of a sample of the affected organ.  Many forms of the disease will produce an elevated blood lymphocyte count; however, similar elevation may also be seen in various chronic diseases.  Treatment should not be initiated until a definitive diagnosis is obtained.

Can lymphosarcoma be treated?

Treatment may not provide a cure, but is designed to prolong good quality of life. Surgery and radiation therapy may be helpful, but are often not effective alone due to the widespread nature of this cancer. Currently the most effective treatment appears to be chemotherapy, with a combination of drugs.  Several protocols have been published for the treatment of lymphosarcoma in the ferret, and variable success rates have been reported.