Due to skeletal concerns, I have always thought that there is sufficient evidence to
not spay or neuter before 14 months of age.
Here is a new study that shows that female dogs live significantly longer than those spayed early. This study shows that females that are spayed
prior to 4.5 years of age have a shorter life expectancy.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2805875/
Take
that to your Vet who wants to spay at 6 months of age ! ! !
I'll be interested to see if a similar study is done on males.
.