Spay
It is recommended, unless other health issues, to allow female OES to go into season/heat once before spay/fixing.
This allows growth plates/hips to fully develop.
Neuter
It is recommended, unless other health issues, to allow male OES to be 2 years of age before neuter/fixing.
Allowing growth plates/hips to fully develop.
Altering reduces not only unwanted pregnancies it has been shown to reduce some types of cancers associated in both female and male dogs.