Chemotherapeutic drugs are used in veterinary medicine to treat a variety of different types of cancers. Many cancers are responsive to the drugs that we have available. Use of chemotherapy often provides our patients the best chance at prolonged survival.
How does chemotherapy work?
Chemotherapeutic drugs stop, or slow the replication of cells. Unfortunately, these drugs are not yet sophisticated enough to only target cancerous cells; other rapidly dividing cells in the body (such as the cells of the gastrointestinal tract and the cells or the bone marrow) are affected as well. It is when these "normal" cells are affected that we see side effects of the drugs.
What are the side effects?
Fortunately, dogs and cats fare much better on chemotherapy than people do. They rarely have any serious side effects. They do not lose their hair. They typically feel pretty good. Most common side effects can be vomiting and/or diarrhea. Often, this will be transient and resolve without medical attention. Sometimes, pets can develop respiratory or bladder infections that would need to be treated with antibiotics.