Lymphadenopathy in Cats

If you pet your cat and feel a lump under the skin, your cat could have lymphadenopathy. Caused by a variety of conditions from infections to cancer, lymphadenopathy is a broad term used when referring to enlarged lymph nodes. 

A lymph node is a bean-shaped organ where infectious material are picked up and destroyed by lymphocytes (a type of white blood cell). When an area of the body has been infected by a microorganism, the duct of the lymph node picks up the excess fluids that have leaked from that area’s blood capillaries and filter the blood toxin, allowing healthy blood to return to the bloodstream. The processes of destroying infectious materials cause the lymph node to become inflamed. Therefore, the area adjacent to the lymph inflammation will pinpoint the location of infection and makes it easy for the veterinarian to diagnose. Lymphadenopathy caused by infections are usually painful to the touch and are accompanied by symptoms associated with the illness. However, lymphadenopathy caused by noninfectious conditions, such as cancer, will cause the lymph node to swell but no pain or accompanying will symptoms will be present. 

The main clinical sign of lymphadenopathy in cats is an enlargement of a solitary lymph node, a regional group of lymph nodes or several regions of the cat’s body. In all cats, the lymph nodes can be palpable on the popliteal nodes, superficial inguinal, axillary, superficial cervical and mandibular locations. A feline may only have an enlarged lymph node and no other signs of illness, but infectious lymphadenopathy usually has accompanying symptoms that vary depending on the area affected. An enlarged lymph node of the neck could cause difficulty swallowing, a decreased appetite, and weight loss. An enlarged lymph node of the limbs could make it difficult for the feline to walk, causing a decrease in physical activity, unusual gait, and swelling of one limb. Other symptoms associated with lymphadenopathy can are specific to the infection or underlying cause, but in general, lymphadenopathy causes symptoms of: 

• A lump underneath the skin
• Localized pain
• Fever 
• Fluid buildup 
• Polyuria 
• Polydipsia 
• Vomiting 
• Diarrhea 
• Lethargy 
• Anorexia 
• Weight loss
• Runny nose

Lymphadenopathy in cats can be caused by neoplastic infiltration, lymphadenitis, or reactive hyperplasia. Neoplastic infiltration is caused by infiltration of metastatic neoplastic disease. Lymphadenitis results from an influx of inflammatory cells usually caused by a localized infection of bacteria, fungi, or a virus. Reactive hyperplasia results from antigenic stimulation of the blood plasma and lymphocyte cells. Examples of common lymphadenopathy causes in cats are listed below: 

• Feline leukemia (neoplasia) 
• Feline lymphoma (neoplasia) 
• Feline immunodeficiency virus
• Histoplasma capsulatum (fungual) 
• Feline coronavirus 
• Toxoplasma gondii (protozoa) 
• Calicivirus polyarthropathy or stomatitis 
• FPV
• FeLV

The veterinarian will begin the diagnostic process by performing a physical exam. If the lymph node is close to the skin’s surface and is not next to an internal organ, the doctor will be able to feel the localized enlargement. Ultrasounds have proven to be most effective in viewing an enlarged lymph node and are the preferred diagnostic imaging choice in most lymphadenopathy cases. Therefore, your veterinarian will likely request an ultrasound of the affected area to pinpoint the exact location. As lymphadenopathy in cats can be caused by several conditions, the veterinarian will begin with a laboratory diagnostic test to analyze the cat’s fluids before moving on to more effusive measures. The laboratory diagnostic tests commonly performed on cats with lymphadenopathy include the following: 

• Complete blood count 
• Serum chemistry profile 
• Feline leukemia virus antigen test
• Feline immunodeficiency virus antibody 
• Serological tests (protozoa infections) 
• Urine antigen titers (fungal infections) 
• Fecal parasitology examination 

If the laboratory tests come back negative for infection or if the veterinarian would like to further exam the lymph node, a cytological examination will be requested. In order to examine the cytological nature of the lymph node, a fine needle aspirate biopsy will be requested to remove fluids or cells from the lymph. The biopsy will then be examined under the microscope by a laboratory technician. 

The treatment option your veterinarian chooses for lymphadenopathy in cats depends greatly on the underlying cause. Infections are generally treated with oral or intravenous medications, focusing on maintaining hydration and terminating the microorganism. Lymphadenopathy caused by cancer, however, is often treated by surgical removal of the lymph node, chemotherapy or radiation therapy. 

In general, lymphadenopathy in cats is not usually serious and most cats make a complete recovery. The cause of lymphadenopathy must be pinpointed to effectively treat and manage the condition, in order to receive a positive prognosis. All unusual lumps on your cat’s skin should always be checked out, even when the feline has no other symptoms, as cancer does not usually cause any clinical signs of disease.