Excerpt from BIRD TALK Magazine, February 2006 issue, with permission from its publisher, BowTie Magazines, a division of BowTie Inc. To purchase digital back issues of BIRD TALK Magazine, click here.
Your bird has developed a lump on the wing, and you schedule an appointment with your avian veterinarian for evaluation of this suspicious mass. Testing uncovers a malignant tumor: cancer. This is the diagnosis that everyone dreads hearing, whether for themselves, a loved one or a pet.
What is cancer? Cancer is a type of neoplasia, which is an abnormal, uncontrolled, progressive growth of cells in any tissue or organ. Neoplasms are classified based upon the general tissue origin, specific cell line type and whether or not the neoplasm is benign or malignant. The group of malignant tumors are considered cancerous.
Cancer is caused by damage (mutations) to the DNA. DNA is like a set of instructions for cells, instructing them how to grow and divide properly. When a mutation occurs in the DNA, normal cells will repair the mutation or simply die off. Sometimes, the cells continue living with the mutation, and, as a result, they grow and divide in a chaotic fashion. One malignant cell becomes two, two become four, four become eight, and so on, until a mass of cells (a tumor) is formed. Tumors eventually interfere with normal body functions and sometimes spread to other parts of the body.
Mutations in DNA can be caused by environmental factors, such as a bird inhaling secondhand smoke (although this has not been proven in birds at this time) or some other toxin. In some cases, it can be possible for mutations to be passed on from one generation to the next. Certain viral infections in birds have been associated with malignancies, too.
For example, birds suffering from papillomas, caused by a suspected herpes virus, seem predisposed to certain malignancies, such as cancer of the pancreas and bile duct. In fact, the papillomas themselves may become malignant or cancerous.
Not all tumors are cancerous, and not all cancers form tumors. For example, leukemia doesn? form one single mass, but causes abnormal cells in the blood, bone marrow, the lymphatic system and spleen.