By eliminating most roaming and fighting, neutering reduces the risk of injury and infection, saving you expensive veterinary bills. Neutered dogs are more content and better behaved.
Neutering reduces aggression against other animals.
A male sensing a female in heat nearby may break down doors and jump fences, and will roam the neighborhood searching for her. Neutering relieves this sexual frustration and lets the dog relax and enjoy being a part of the family. Dogs have no psychological sex drive. They feel no need to reproduce, and are happier when they're neuterd. Neutering is a relatively safe and painless operation done by a licensed veterinarian.