What Is Lymphoma? (AKC)

Scientifically speaking, lymphoma is a blanket term doctors use to describe a group of cancers that occur due to a change or overgrowth of lymphocytes. Lymphocytes are a type of white blood cell that helps the immune system fight off infection and are highly concentrated in organs that play an important role in the immune system. Organs like the lymph nodes, the spleen, and bone marrow are heavily affected by changes in lymphocyte levels. Most lymphoma cancers are found in these organs, but lymphoma can affect any organ in the body. (AKC)

Lymphoma – Human (NIH)

The immune system protects the body from foreign substances, infection, and diseases. The lymph system is made up of the following:

• Lymph: Colorless, watery fluid that carries white blood cells called lymphocytes through the lymph system. Lymphocytes protect the body against infection and the growth of tumors. There are three types of lymphocytes:
  • B lymphocytes that make antibodies to help fight infection. Also called B cells. Most types of non- Hodgkin lymphoma begin in B lymphocytes.
  • T lymphocytes that help B lymphocytes make the antibodies that help fight infection. Also called T cells.
  • Natural killer cells that attack cancer cells and viruses. Also called NK cells.
• Lymph vessels: A network of thin tubes that collect lymph from different parts of the body and return it to the bloodstream.
• Lymph nodes: Small, bean-shaped structures that filter lymph and store white blood cells that help fight infection and disease. Lymph nodes are located along the network of lymph vessels found throughout the body. Clusters of lymph nodes are found in the neck, underarm, abdomen, pelvis, and groin.
• Spleen: An organ that makes lymphocytes, filters the blood, stores blood cells, and destroys old blood cells. Thymus: An organ in which lymphocytes grow and multiply
• Tonsils: Two small masses of lymph tissue at the back of the throat. The tonsils make lymphocytes.
• Bone marrow: The soft, spongy tissue in the center of large bones. Bone marrow makes white blood cells, red blood cells, and platelets.
• Lymph tissue is also found in other parts of the body such as the stomach, thyroid gland, brain, and skin. Cancer can spread to the liver and lungs. (NIH)

Types of Lymphoma in Dogs (WebMD)

Dogs can get over 30 types of lymphoma. They vary in how fast they spread, the symptoms they can bring on, and how long dogs tend to live with them.

Your vet might diagnose your dog with one of these four:

• Multicentric lymphoma.This is the most common kind of canine lymphoma. Up to 85% of cases are this type, which first affects the lymph nodes.
• Alimentary lymphoma (also called gastrointestinal lymphoma).This is the second most common type, and it makes up less than 10% of cases of lymphoma in dogs.
• Mediastinal lymphoma. This rare type enlarges certain parts of the lymph system (tissues and organs that make, store, and carry white blood cells) in or around the chest. It can cause a lump or fluid buildup that makes it harder for your dog to breathe.
• Extranodal lymphoma (including cutaneous lymphoma).This type affects a specific organ or set of organs, like the skin, eyes, kidneys, lungs, or central nervous system. Most of the time, it affects the skin (called cutaneous lymphoma). It may also affect the gums, lips, and roof of the mouth. (WebMD)