Cancer is the leading cause of death in dogs over age 10, and navigating treatment decisions requires careful attention to quality of life throughout the process.
Cancer treatment decisions in companion animals are among the most ethically complex in veterinary practice. Unlike in human medicine, patients cannot participate in treatment consent or communicate their experience directly. The central welfare question is whether treatment extends life while maintaining or improving quality of life, or merely prolongs suffering. Veterinary oncology has developed quality of life assessment scales — such as the HHHHHMM scale — to help quantify comfort, pain, appetite, mobility, and joy. Treatment should never be pursued if it causes suffering exceeding benefit. Palliative care, pain management, and clear criteria for euthanasia when quality of life becomes unacceptable are as important as curative options. Supporting owners through these decisions is a core responsibility of veterinary practice.