This is a hot topic in the past 10 years when it comes to pets. Vets and shelters push for an early spay/neuter to help with overpopulation, but a lot of recent studies have shown that there can be complications due to spaying or neutering your pet too early. We personally recommend waiting until your dog is at least 12 months in age before neutering, preferably longer. It is ultimately down to what you can handle as a pet owner. Facts:
Large Breed dogs with deep chests such as German Shepherds have growth plates that take anywhere from 18 to 24 months to close. Dogs Spayed or Neutered before the closing of the growth plates were found to be taller and longer boned (more gangly) than their intact siblings. When you see the father of your puppy at 5 years as compared to 2 years, you would see the major difference. Neutered and spayed dogs don’t “bulk out” as they normally would due to the lack of hormones to support them. This can take away from the presence of the German Shepherd.
A study done in 2013 using Golden Retrievers found that males neutered before the age of 12 months had double the risk of developing hip dysplasia than their intact littermates.
Two studies done for dogs who were spayed and neutered before the age of 6 months showed as much as a 70% increased risk for Hip dysplasia. (Victor Spain , van Hagan)
Whitehair et al (JAVMA Oct 1993), found that spayed and neutered dogs of any age were twice as likely to suffer cranial cruciate ligament rupture. Slauterbeck et al also found an increased risk (Clin Orthop Relat Res Dec 2004).
The Golden Retriever study looked at cancer rates and found that the incidence of lymphosarcoma was three times higher in males neutered before 12 months of age. Interestingly the percentage of hemangiosarcoma in females spayed after 12 months was four times higher than that of intact and even early-spayed females. Additionally, 6% of females spayed after 12 months were affected with mast cell cancer, while there were zero cases among the intact females.
A recent study on Vizslas showed that the incidence of all cancers in spayed females was 6.5 times higher and in neutered males was 3.6 times higher than intact dogs. They also found that the younger the dogs were spayed/neutered, the younger they were when diagnosed with cancer.
In the Vizsla study, they found that spayed and neutered dogs were also more likely to develop behavior disorders than intact dogs. The original idea of a more mellow companion through spaying/neutering was theorized because they knew that dogs that did not have as high of a sex drive were less likely to wander if they smelled another intact dog in season. While this is true, they found that the sterilized dogs had more fears and anxieties than intact dogs, and some studies pointed to them being more aggressive, excitable, and less trainable.
The hormones produced by the reproductive organs removed during a spay/neuter are responsible for the development of homeostasis, body condition, cholesterol levels, energy levels, urinary continence, muscle tone, cognition, behavior, a major role in the development of their immune system. (Article here)