Female dogs are spayed by removing their reproductive organs, and male dogs are neutered by removing their testicles.
Your veterinarian can fully explain spay and neuter procedures to you and discuss with you the best age at which to sterilize your dog.

Spaying or neutering dogs is good for both of you:

• Prevents messy spotting of blood in female dogs during heat periods
  
• Spaying eliminates the possibility of uterine or ovarian cancer and greatly reduces the incidence of breast cancer, particularly when your dog is spayed before her first estrous cycle.
  
• Neutering eliminates testicular cancer and decreases the incidence of prostate disorder.
  
• Spaying or neutering dogs reduces dog behavior problems, eliminates internal fighting, irritable aggression of females in heat, and dominant dog behavior. Neutering does not affect guarding behavior.
  
• Spayed or neutered dogs will NOT become lazy or fat, lack of exercise does that.
  
• Spayed or neutered dogs may require less food...and that means money saved.
  
• Spaying or neutering dogs reduces roaming which means your dog will be less likely to get into dog fights, become lost, injured, or hit by a car.
  
• Spaying or neutering helps dogs live longer, healthier lives. It makes happier dogs.