Cancer is the leading cause of death in many dog breeds, with genetic risk concentrated through intensive selective breeding creating significant welfare burdens.
Cancer in dogs causes suffering that intensifies as the disease progresses, often including pain, nausea from chemotherapy, respiratory distress from tumors, and the trauma of palliative procedures. Breed-specific cancer risk represents a welfare consequence of genetic bottlenecks created by closed stud books and popular sire effects that concentrate deleterious mutations. The golden retriever cancer crisis has driven significant research funding through the Morris Animal Foundation Golden Retriever Lifetime Study, a longitudinal cohort following 3,000 goldens from puppyhood to reveal environmental and genetic cancer risk factors. Welfare-conscious breeding should incorporate cancer screening and selection against identified cancer risk alleles alongside physical and behavioral traits. Early detection enables earlier intervention and potentially better outcomes, while end-of-life planning frameworks help owners make welfare-focused decisions when treatment options are exhausted.