Castration is the most common procedure for neutering male dogs. For females, ovariectomy has become the procedure of choice in most of Europe. Ovariohysterectomy remains the most common procedure in the United States, United Kingdom, and Canada.^78–80 Any sterilization procedure has potential behavior and health benefits and concerns that should be completely discussed with owners.^81–83For example, hysterectomy with retention of ovaries may warrant further consideration as an alternative to complete ovariohysterectomy as it may be helpful to avoid certain conditions later in life (e.g., hormonally responsive urinary incontinence, transitional cell carcinoma).^84–86 Some sex-associated unwanted behaviors may be prevented with spaying/neutering.^85,87,88

Shelter and rescue groups promote early spay and castration prior to adoption to reduce pet over-population.^89,90 Neutering of pediatric animals has been endorsed by the AVMA as a means of reducing the numbers of unwanted cats and dogs.⁹¹ Spaying female dogs before 2. 5 yr of age may reduce the risk of mammary tumors (the most common tumors in female dogs) and nearly eliminates the risk of pyometra.^92–95

Coordinating surgical sterilization with permanent dentition eruption (particularly in small breeds prone to persistent deciduous teeth and unerupted first mandibular premolars) allows the identification and correction of dental abnormalities under a single anesthetic episode.