This condition, called lymphoid hyperplasia, may also be associated with a variety of inflammatory and infectious diseases, such as Crohn's disease, gastroenteritis, respiratory infections, mononucleosis, and measles.
Most of these are cancers of the lymphoid tissues (leukemias and lymphomas), but one fifth of the cancers occur in the stomach, brain, ovary, skin, liver, larynx, parotid gland, and breast.
Beyond its normal growth pattern, lymphoid tissue grows excessively (hypertrophies) during an acute infection, as it suddenly increases its immune activity to fight off the invaders.
Lymphoid tissue, which is present in mucosal lining of the appendix and intestines to help fight bacterial and viral infections, can swell and lead to obstruction of the appendix.
The virus is believed to enter the body through the mouth with primary multiplication occurring in the lymphoid tissues in the throat, where it can persist for about one week.
Acute lymphoid leukemia (ALL) is more common among Caucasians than among African-Americans, while acute myeloid leukemia (AML) affects both races equally.
In chronic lymphoid leukemia, 90 percent of the cases are seen in people who are 50 years or older, with the average age at diagnosis being 65.
Once the virus gains admittance into the puppy's system it begins to replicate in the lymphoid tissue and spreads into the blood stream.
In contrast to the rest of the body's tissues, lymphoid tissue reaches its greatest size in mid-childhood and recedes thereafter.
According to statistics, in chronic lymphoid leukemia, the overall survival for all stages of the disease is nine years.