As a survivor of lymphoma (cancer of the lymphatic system,) I get many questions about lymph nodes and what they are.  One aspect of the body ™s defense system is the army of white blood cells which are designed to fight infection.  One type of white blood cell, the lymphocyte, helps to make antibodies.  Lymphocytes are produced in the bone marrow.  While some float freely in the blood, most of them hang out together in groups, called lymph nodes.  These nodes can be found all over the body in predictable locations.  When you go to the doctor and he palpates under your chin towards your neck, he is checking a set of lymph nodes.  When we examine pets, we palpate lymph nodes near the neck and shoulders, in the armpits, in the groin and in the back of the legs.  Lymph nodes are also found in the chest and abdomen.  There is actually a second circulatory system that runs fluid through these lymph nodes.  Here the lymphocytes can grab infectious or foreign material, trap it, analyze and try to make antibodies to destroy it.
Lymph nodes will become enlarged if there is any inflammation in the area of the node, or if the node is cancerous.  Lymphoma usually involves more than one lymph node, but can occur in a single node.  Determining why a lymph node is enlarged requires a complete physical exam and either an aspirate or biopsy of the node.
The doctors at Animal Care Clinic have much experience treating lymphoma, one of the most œtreatable  of pet cancers.

by Bonnie Markoff, DVM, ABVP