Osteosarcoma Risk 
I have edited the statement regarding the association between neutering and osteosarcoma (OSA) because it was far stronger than the citation, or the literature in general, supports. In a single study of a single breed with a known risk for osteosarcoma far higher than most other breeds, the data showed the total lifetime exposure to sex hormones was negatively correlated with the incidence of OSA. The incidence of the disease was not statistically different between neutered and intact animals overall, though it was different between animals neutered at less than 1 year of age and intact animals. And there is no reason to suggest these findings would support a general relationship between neutering and OSA incidence in other breeds or mixed-breed dogs. Given the questionable clinical significance of the finding (intact animals actually died slightly, though not significantly, earlier than neutered animals overall) and the much more thoroughly demonstrated protective benefits of neutering on life expectancy and other kinds of cancer, I do not find this study sufficient to support a general assertion that OSA risk is a meaningful disadvantage of neutering.

Brennen McKenzie, MA, VMD