The appearance of swollen lymph nodes on a pet can be a cause of concern for the owner. A dog with swollen lymph nodes should be seen by a veterinarian for proper diagnosis and treatment. While enlarged lymph nodes can indicate serious health issues, such as a mast cell tumour, they can also indicate a less serious issue, such as a bacterial infection.
The canine lymphatic system contains more than just lymph vessels and lymph nodes. It also includes bone marrow, the thymus and the spleen, all of which work with the dog's cardiovascular system to return fluids from blood vessels. The lymphatic system is also an important part of the immune system, helping the dogfight off illness and disease.
Mast cells originate in the bone marrow. They aid in fighting inflammation, illness or parasites. Mast cells are rarely found circulating in the blood and usually are in the tissues, lymph nodes and lymph vessels. When illness or infection occurs, the number of mast cells in the lymph nodes increases.
Mast Cell Cancers
Mast cell cancers do not always occur in the lymph nodes; up to 20 per cent of all skin tumours in dogs are mast cell tumours. Mast cell tumours are invasive and can spread quickly into other areas, including the lymph nodes or organs within the lymphatic system such as the liver or spleen. Treatment for mast cell tumours generally involves removal of the tumour. Depending on the severity of the tumour, prognosis can vary from excellent to poor.
Other Lymphatic Illnesses
Many other illnesses and diseases can affect the canine lymphatic system besides mast cell cancer. Lymph nodes can become infected by viruses, fungi and bacteria. Other lymphatic-related diseases include lymphadenitis, mammary cancer, Lyme disease and even the plague, a bacterial infection spread by fleas.