Spay and neuter surgery prevents unwanted litters and reduces shelter overpopulation, but emerging research on hormonal health effects has refined recommendations about optimal timing and approach.
The welfare calculus around spay and neuter has become more nuanced as research has accumulated on the long-term health effects of removing hormonal influences on development in dogs and cats. Early spay-neuter in large-breed dogs is associated with increased risk of certain orthopedic conditions and cancers due to the role of sex hormones in development. These findings have led veterinary organizations to refine recommendations toward later timing for large breeds while maintaining the core message that preventing unwanted reproduction is a welfare necessity. The development of hormone-sparing surgical alternatives expands options for balancing individual and population welfare considerations.