What are the pros and cons of spaying my dog?

Presently, there's a lot of controversy over when it's appropriate to spay/neuter a dog.

Pros - prevents certain cancers, improves behavior, avoids pregnancy and unwanted pets.

Cons - sterilization may cause certain cancers, leaking, behavioral issues.

The jury is still out on both the pros and cons. Some researchers  feel dogs should be sterilized only after their bones have had time to fully develop. For now, I'd prefer to err on the side of spaying.