But ... I don't understand if you don't want the dog to breed why not just spay/neuter?
Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs
EVIDENCE-BASED APPROACH TO NEUTER SURGERY AND INTRODUCTION TO EVIDENCE-BASED MEDICAL PRACTICE
Pros and Cons of Neutering
Non-reproductive Effects of Spaying and Neutering
New Views on Neutering
ISSUES REGARDING CASTRATION IN DOGS
Will We Change on Early Spay-Neuter?
NEUTERING MALE AND FEMALE DOGS
A Veterinary "Review" Article on Neutering, with Implications
for Dalmatian Stone-Formers
Determining the optimal age for gonadectomy of dogs and cats
The Effects of Spaying and Neutering on Canine Behavior
Revisiting The Idea Of Early-Age Neutering
Benefits & Risks of Neutering
Endogenous Gonadal Hormone Exposure and Bone Sarcoma Risk
Exploring mechanisms of sex differences in longevity:
lifetime ovary exposure and exceptional longevity in dogs
Message for women and dogs: keeping ovaries is linked to longevity
A Healthier Respect for Ovaries
Now, some of these are more opinionated than others but most lay out a nice idea of pros and cons.
ETA: I can't believe I didn't get moderated for this massive post of links!