What are the causes of swollen glands in the armpit? What are the symptoms of swollen lymph nodes in dogs? How do vets diagnose swollen lymph nodes?

What Are Swollen Lymph Nodes in Dogs?

The lymphatic system is part of your dog’s immune system. It includes lymph nodes and a network of lymph vessels called lymphatics that run alongside your dog’s regular blood vessels. The lymph system performs several important functions in your dog’s body, including transporting white blood cells, removing waste products from tissues and cells, and helping to produce disease-fighting antibodies.

Lymph nodes are small, bean-shaped organs that contain immune cells. When your dog’s body is invaded by viruses or bacteria, or your dog has a disease that triggers an immune response, the lymph nodes become enlarged as they work to fight off the invader. Swollen lymph nodes are called lymphadenopathy or lymphadenomegaly.

How Can You Tell if Your Dog Has Swollen Lymph Nodes?

Your vet can tell the difference between swollen lymph nodes and regular lymph nodes by feeling the lymph nodes that are closer to the skin. Lymph nodes that can be felt through the skin are known as “palpable” nodes. These are located in a few areas:

• Submandibular: Just under the jaw where it meets the neck
• Pre-scapular: Under the submandibular lymph nodes at the front of the shoulders
• Axillary: In the “armpit” of the dog, or where the front legs meet the chest
• Inguinal: On the underside of the dog where the rear legs meet the abdomen (groin)
• Popliteal: Just behind the stifles (“knees”) of the rear legs

What Are the Symptoms of Swollen Lymph Nodes in Dogs?

In most cases, there are no outward symptoms that accompany your dog’s swollen lymph nodes, particularly if they are only mildly enlarged. However, if the lymph nodes are significantly enlarged—including the nodes inside the thorax and abdomen—then you should watch for symptoms including:

• Vomiting
• Coughing
• Lethargy
• Fever
• Poor appetite
• Enlarged abdomen

What Causes Swollen Lymph Nodes in Dogs?

Lymph nodes enlarge when the immune system is activated, usually by a disease process. If just one or two lymph nodes are enlarged, this often indicates a localized disease. For example, an infected toe could result in enlarged lymph nodes that drain that area.

A systemic infection in which the whole body is affected will often cause many or all of the lymph nodes to be enlarged. Examples include:

• Demodectic mange
• Puppy “strangles” (i.e., juvenile cellulitis)
• Tick-borne diseases (e.g., Lyme disease, ehrlichiosis)
• Bacterial infection (e.g., Yersinia pestis, which causes canine plague)
• Reactive hyperplasia (e.g., active immune response)
• Fungal infection (e.g., Coccidioidomycosis)
• Immune-mediated diseases (e.g., pemphigus)
• Cancer (e.g., lymphosarcoma)

Are Certain Dog Breeds More Prone to Swollen Lymph Nodes?

There aren’t specific breeds that are susceptible to swollen lymph nodes. However, some breeds are susceptible to diseases that will cause swollen lymph nodes. Other breeds are prone to developing lymphosarcoma (cancer of the lymphatic system), including Golden retrievers, Boxers, Dobermans, Rottweilers, and others.

Toy breeds (such as Yorkies, Poodles, and Dachshunds) are very susceptible to dental disease, and often have enlarged submandibular lymph nodes when they have infected teeth and gums.

How Do Vets Diagnose Swollen Lymph Nodes?

Enlarged lymph nodes are usually fairly obvious on physical exam. If your vet finds swollen lymph nodes, they may collect a sample through one of these methods:

• FNA: Fine needle aspirate (FNA) is a procedure in which a syringe and needle are used to collect cells that can be examined under a microscope. Your vet will examine these cells on a slide, or they might send the sample out to an outside lab for analysis.
• Biopsy: In some cases, your vet may recommend a biopsy, which involves surgically removing a small sample of the lymph node for more extensive analysis.

Depending on the results of these tests, your vet will work to determine the underlying cause of the swollen lymph nodes and develop an appropriate treatment plan.