There are good reasons to spay and neuter. Population control is a major issue. Additionally, spaying female dogs before they go into heat the first time reduces their risk of developing breast cancer to zero. On the other hand, spayed and neutered dogs have a 40% greater risk of developing cancers– osteosarcoma and malignant lymphoma. The question is whether we can have the best of both options.
Bio-identical hormone replacement therapy (BHRT) for people has been developed over the past 30 years. BHRT utilizes hormones which are the same as those already in the body in physiologic doses. Blood tests are used to make sure that serum levels of hormones remain in the range that is normal for sexually intact animals. One major difference between dogs and humans in regard to BHRT is that therapy for dogs begins at a much younger physiological age. At present, it is not known if that would have any detrimental effects. But when one considers that 50% of pets develop cancer, it would appear that the potential benefit is worth assuming some risk.