According to the Animal Cancer Center, at Colorado State University, cancer is the most common natural cause of death in dogs and cats in the United States. Close to 50% of dogs and cats will develop cancer if they live ten years or longer. Traditional Chinese Medicine (TCM) has been used for the diagnosis and treatment of tumors since the Warring States Period (475 to 221 BC), when “Ling Shu Jing” (Miraculous Pivot) stated “the tumor was caused by the pathological factors which had stayed in the body over a long time”. The etiology and pathology of cancer from a traditional Chinese medicine perspective is presented along with Chinese herbal formulas to address the patterns of imbalance.