Most veterinarians do advocate spaying or neutering any dog or cat not being used for specific breeding purposes. Population control of our pets is very important since unwanted animals are taken in by humane societies and animal control authorities daily. Many animals are euthanized on a routine basis due to overpopulation. Sterilizing your pet is the best way to protect against the overpopulation problem.
In addition, sterilization has many behavioral and medical advantages. Spayed/neutered pets interact much better with other pets and with people, thereby, decreasing the risk of injury. Given the increasing density of both pets and people living together in cities, this can be very important. Urine marking in both male dogs and male cats is another behavioral reason for spaying/neutering our pets. Medical reasons include decreasing or even eliminating the risk of serious diseases such as uterine infection (potentially fatal), uterine or ovarian cancer, mammary cancer, testicular cancer and prostate disease.
Most veterinarians recommend spaying/neutering at around 6 months of age. This is after your pet has completed his/her set of puppy/kitten vaccines but before sexual maturity. At this time your pet is protected from picking up diseases from the animal hospital, but not yet at risk for behavior or medical problems associated with sexual maturity.
Other problems that have been noted by your veterinarian during the early examinations can also be dealt with at this time. Such things include hernia repair, removing retained baby teeth, hip radiographs (for hip dysplasia), etc.