Cancer is the leading cause of death in dogs over ten years old, requiring careful welfare assessment alongside treatment decisions.
Cancer diagnosis in a dog triggers complex welfare and ethical decisions for owners. Veterinary oncology has advanced substantially — chemotherapy protocols designed for dogs cause milder side effects than human equivalents because doses are lower, extending life without severe suffering in many cases. But the welfare calculus requires honest assessment: some cancers have poor prognoses despite aggressive treatment, and prolonged treatment may extend the quantity of life while reducing its quality. Quality of life scoring tools such as the HHHHHMM scale help owners assess whether their dog is experiencing more good days than bad. Palliative care — pain management, anti-nausea medication, appetite support, and comfort care — is a legitimate welfare-positive choice when curative treatment is declined. The decision to euthanise a suffering dog is a welfare act, not a failure.