While sterilizing your pet is a very safe, very common procedure, there are a few things you'll have to keep in mind. Your vet will no doubt advise that you not feed your dog for at least eight hours before surgery. The dog will be given pre-anesthetic drugs to reduce anxiety, and to get his body ready for the general anesthetic. With an IV hooked up to his shaved forelimb or hindlimb, the sedative will allow the vet to insert a tube through your dog's mouth into his windpipe to administer gas anesthetic and oxygen.
For females, the ovaries, uterus and most of the cervix are removed through an incision in the abdomen. For male castration, the vet makes an incision in or near the scrotum and removes the testes. Your dog will awaken soon after the stitches are tied. He or she might be in pain, so make sure your vet has prescribed painkillers. Never decide on your own to use human painkillers. They can be toxic.
Usually you can bring males home a few hours after the surgery, but females will often be kept overnight. Both will be back to normal in one or two days. Monitor your dog's health, and watch for fever, swelling, vomiting or discharge. Keep the affected area clean and dry. Usually you can begin feeding small meals and water a day after surgery.