Cancer is the leading cause of death in dogs over 10. Veterinary oncology offers treatment options that can extend quality life, but welfare during treatment requires careful monitoring and honest assessment.
Cancer welfare in dogs requires ongoing assessment of whether treatment benefit outweighs treatment burden. Most dogs tolerate chemotherapy well compared to human patients because protocols are designed for quality-of-life maintenance rather than maximum cell kill. However, some dogs experience significant nausea, fatigue, and immune suppression that requires treatment modification. The welfare calculus changes over the course of treatment - a dog in early remission who is eating well and active may have excellent quality of life despite being in active chemotherapy. A dog approaching end of first remission with declining body condition and reduced enjoyment requires honest reassessment of whether continued treatment serves their welfare. The primary goal of cancer treatment in dogs should always be quality life, not maximum duration.