There's a new-ish
study out that links the time a dog (specifically a Rottweiler) is spayed with their subsequent longevity. Specifically, the results of the study indicate that dogs spayed after they are 6 years old were 4.6 times as likely to reach 13 years of age.
Currently, the recommendation in the US is to spay before the dog's first heat cycle or before they turn a year. And there are still some good reasons to spay early, not least of which is that many, many people are not set up by either lifestyle, inclination, or education to have a breedable female dog in their household for six years and we have far too many stray and unwanted pets already. Also, of course, this is one study with a relatively small number of dogs (because, sadly, it's not easy to find Rottweilers who live to 13).
My first dog, Riley, is a part of this study, which has been going on for years and began as a way to look at dogs and cancer. She is in the control group for the longevity part of the study because she died at the 'normal' age of 9.5 years. The researchers call periodically with followup questions. In fact, this week they called to ask why I spayed her when I did (8 months) as questions were raised that maybe the early-spay dogs were spayed early because there was something wrong with them.
I love knowing that one of my dogs is a part of this study and so, maybe, gets to help other dogs and people (because most of this stuff applies). I wish John Henry was in the data mix as well, though at the time I don't think he hit their birth date cut off. He was a poster child for longevity, though, living to 12.5 and 2.5 years after his diagnosis for bone cancer.