The timing of spaying and neutering has significant health and welfare implications — the evidence base has evolved substantially beyond simple early-age recommendations.
The welfare evidence on spay-neuter timing has evolved significantly, challenging the historical norm of early-age neutering for all dogs. It is now clear that gonadal hormones play important roles in musculoskeletal development, immune function, and behavior — and that removing them before skeletal maturity increases risk of certain orthopedic conditions and cancers in some breeds. This does not mean neutering is harmful — the risks of intact dogs including mammary cancer, pyometra, testicular cancer, and behavioral problems are also real. The welfare-centered approach involves individualized decision-making based on breed, sex, lifestyle, and owner capacity to manage an intact animal responsibly. Consulting a veterinarian who is familiar with current evidence is essential.