The short answer is; Quality breeders do not want their puppies (or descendants carrying their kennel name) to fall into an improper breeding program by accident or ill design. Reputable breeders go to great lengths to make sure they do not contribute to pet overpopulation and burden the already overcrowded dog rescues.
Reputable breeders sell "pet" puppies on an AKC “Limited Registration”. This ensures that any puppy produced by a dog or bitch with a limited registration cannot be registered with the AKC.
Reputable breeders will also have a puppy sales contract requiring the puppy buyer to have their animal spayed or neutered. In most cases the contract will go further and not allow breeding.
Golden Retriever Rescue Organizations spend thousands of dollars each year to save unwanted Goldens. Most of these dogs became "rescues" because their owners had little idea of the time, commitment and effort it takes to own a sporting dog. The dogs that don't make it to the rescue organizations are usually uthanized in County Animal Control Shelters. Spaying & neutering would have prevented the majority of these killings.
One source of this problem is "Backyard Breeders". The other major source of rescue dogs are the "Puppy Mills" and animal brokers that wholesale to pet shops and are only focused on profit. I'll do a rant on mills in a future post.
Some of the benefits of spaying include not having to worry about accidental breeding, the stress and inconvenience of confining a bitch in season, "mismating" or creating unwanted puppies. A spayed bitch will not develop uterine infections or tumors of the reproductive system, as do some older unspayed bitches.
Males may be easier to control and healthier longer-term. However, the basic attitude and temperament of the animal is NOT changed by removing the reproductive capability.
Having a dog spayed or neutered at the right time will not affect your dog's health, weight, energy level or quality. It may actually improve their overall health and longevity.
The studies we have seen and the research we have read has convinced us that Goldens should be neutered or spayed after reaching maturity. That's around two (2) years of age. Do not spay/neuter too early (as many Vets recommend).
Males should have an adult physique (heavier bone, muscle definition, broadened head, etc.). Females should also have lost the puppy and teenager type features and have gone through at least one season or cycle.
If you want the latest information (May 2014) on Spay/Neuter the Golden Retriever Club of America (GRCA) has created an excellent recap of Health Consideration for early Spay/Neuter. Print & share this with your Vet is they are suggesting early Spay or Neuter.
The AKC web site has several articles worth reviewing. Here's a couple of links:
Should I Breed My Dog?
AKC Defines The MINIMUM Steps Involved For Responsible Dog Breeding
Also visit the Golden Retriever Club of America - National Rescue Committee FAQS page for additional information www.grca-nrc.org.