Metastatic cancer in dogs occurs when cancer has spread from its site of origination to other organs or tissues within the body. In general, the prognosis for treating cases of metastatic cancer in dogs depends on how early the metastatic tumor is identified and how invasive it is. The best way to increase a dog's prognosis against metastatic cancer is to be aware of the signs and to detect it early enough that treatment can be successful.
Metastatic Cancer Explained
Cancer in dogs has the unique ability to reproduce and regenerate in another area separate from the original site. This is known as metastasis, and it is a secondary type of cancer in dogs. The main highways of travel for cancer cells are the bloodstream and the lymphatic system (lymph nodes). Metastatic tumors in dogs are made up of cells of the original tumor, not the site in which they have moved to.
For example, in the case of metastatic lung cancer in dogs, the tumor originates in the lungs and moves elsewhere throughout the body. The location of that metastatic tumor will then consist of lung cells, not the cells of the area in which it spreads to. It is important to be aware that metastatic cancer can spread to any area of a dog's body, but it is more common for it to spread to either the lungs or the bones.
Signs and Symptoms
The symptoms of metastatic cancer in dogs are not universal. In general, symptoms develop based on where the metastatic cancer is located, how invasive it is and how long it has been present. When metastatic cancer spreads to the bones, the primary symptoms may be hesitancy to walk around or climb stairs, or anything that would cause pain to the dog's bones and joints. Metastatic tumors affecting the kidneys may create limited kidney function, giving way to problems with excessive urination, increased thirst and generalized weakness.
Any type of cancer in dogs can produce the following symptoms:
- Vomiting
- Shortness of breath
- Reduced appetite
- Excessive thirst
- Excessive weight loss
- Hacking and coughing
Diagnosing Metastatic Cancer
On most occasions, the primary cancer will be identified well before any metastasis occurs. In other cases, metastatic cancer may produce symptoms before the original tumor is even diagnosed.
Typically, the first test to be performed is a blood test. This will check for abnormalities in protein, blood sugar, electrolyte balance, white blood cell count, red blood cell count, kidney function, liver function and so on, all of which can be drastically affected by the onset of cancer in dogs. When this test produces an abnormal finding, and combined with the cancer-like symptoms, an x-ray of the area in question is usually performed to determine if any tumors are present.
Treating Metastatic Cancer
In general, treatment of metastatic cancer in dogs depends on the stage of the cancer and the location. In most cases, radiation therapy may be used to help reduce the size of the tumor and destroy the cancerous cells. Other times, surgical removal of the tumor may be appropriate. In cases where the dog is in the end stages of cancer prognosis, it may be best to provide therapeutic and comforting medications rather than attempting treatment.