Chemotherapy: Historically, the word “chemotherapy” referred to the use of any chemical in any medical treatment. Today, it is used to describe the use of pharmaceuticals in a cancer treatment. Chemotherapy kills cancer cells in a variety of different ways, including: increasing damaging free radicals within cancer cells, damaging DNA, blocking cell division, interfering with cell metabolism, and increasing apoptosis. Often there is a blend of different processes leading to cytotoxicity. Chemotherapy drugs are usually administered intravenously or by mouth, depending upon the drug. Typically, the goal is to give the dog the maximum tolerated dose, although lower doses are used in metronomic chemotherapy. Dogs do not usually require sedation or anesthesia during chemotherapy treatments.