Ethical issues Caring for cancer patients presents many ethical issues for veterinarians and other veterinary health workers. The issues that most veterinarians think of relate to management of the patient when the owners’ preferences for treatment do not appear to be in the animal's best interest, as well as concerns about toxicities and about costs of veterinary services (advanced imaging, surgery, radiation therapy and chemotherapy). While not limited to the veterinary profession, we are more often faced with dilemmas about the appropriateness of palliative care and decisions about euthanasia than our medical colleagues. Equally important are the ethics of not treating patients, and the integration of unproven and alternative strategies into conventional care. A separate ethical issue arises from investigational therapies and research. Less often considered, but nonetheless relevant, are the ethics of suboptimal evaluation (staging) of patients prior to treatment, or of not informing owners about all the options available. Client communication Ethical veterinary care is intertwined with good client communication. Without good communication, it is impossible, for example, to gain informed consent; and without informed consent, the ethics of cancer treatment are uncertain. Goal This article, which draws in part on published research, where stated, and otherwise on the author's personal experiences/opinions and those of veterinary colleagues, is intended to provoke further thought and discussion on the ethics of caring for our cancer patients.