If you do not want to breed your cat, please have it neutered. for  its own health and as a contribution to reducing the pet population. It  is not true that neutering causes obesity and laziness; overeating and  getting too little exercise are to blame.

The best time for the female's ovario hysterectomy is before the  first heat (but not before five or six months of age). The estrogens  secreted during the heat period may prime the breast tissue for later  tumor development. and approximately 90percent of them are malignant.  Spaying early may help prevent tumors from developing.
The ovario hysterectomy is the surgical removal ("ectomy") of  ovaries ("ova-rio") and the uterus ("hyster") through an abdominal  incision. The size of the incision does not indicate your doctor's  surgical skill. Some doctors make small incisions, and others like to  have good exposure of the surgical area. The size of the organs to be  removed will vary among animals as well.
Spaying is common surgery, but every pet is unique. and special  care will betaken. A careful and thorough preoperative exam will  determine your cat's ability to undergo surgery. Modern anesthesia (gas  or inhalants) is very safe: an anesthetic caused death is extremely rare  in a healthy pet. Your doctor will instruct you not to feed your cat  for twelve hours before surgery, which will allow the stomach to empty.  If there is food in the stomach during surgery, it may be vomited and  pass into the breathing tubes and lungs, and an aspiration pneumonia  could occur.If the monitoring equipment (which keeps track of breathing  and heart functions during surgery) indicates a potential problem, your  cat can be brought out of the anesthesia in a few minutes. Many  veterinary hospitals have the same heart monitors used for humans in  hospital intensive care units. Emergency fluids and drugs,which are  rarely needed, are readily available.
Postoperative complications (such as infection) are also very  rare because of aseptic surgical techniques: the operating room is well  sterilized, as are the instruments, drapes, caps, masks, and gowns.  Modern anesthetics allow most cats to be on their feet minutes after  surgery, which also probably lessens the postoperative discomfort. Your  cat may be home the same day or the next day, depending on the  veterinary hospital procedure.
Home care after surgery consists of keeping the incision clean  (don't allow your pet to lie on dirt), restricting your cat's exercise  (cats will normally restrict their own activity), and checking the  incision for swelling, redness, or discharge. If any infection develops,  call your doctor. The sutures can be removed in a week.
Castration (surgical removal of the testes) is recommended to  prevent or eliminate roaming, spraying, fighting, and breeding in male  cats. The testicles are removed through a very small incision in each  scrotal sac after the cat has been anesthetized. Most cats are sent home  the same day, and surgical recovery is un-eventful. In fact, when our  male cat CPU was castrated, he was out of the anesthesia in five  minutes. I drove him home shortly afterward, and no sooner had we  arrived home than he gobbled down some cat food and briskly mounted  Mitzi, our tolerant female Siamese! Now that's what I call a recovery!
It may take up to a month for the roaming, spraying, fighting,  and mounting behavior to stop, because it will take a few weeks for the  male hormones still circulating in the body to be used up. A very small  percentage of cats may still have some residual objectionable behavior.  The best time for the surgery is before the behavior patterns develop -  about six months of age.
Rarely, a male cat will have only one testicle (monorchid) or  none at all(cryptorchid) in the sacs (scrotum). Although sperm will not  be produced in the undescended testicle, male hormones will still be  manufactured: your cat will continue to strut around like the  neighborhood lover. One problem with undefended is that they frequently  form a large sterol cell tumor after seven years of age. Again, this is  extremely rare in cats.
If your female cat has been misdated (accidentally bred), an  estrogen injection, followed by estrogen tablets given at home, is  usually successful at preventing pregnancy if given within twenty-four  hours of the breeding. The injection makes the uterine environment  hostile to the sperm and egg; therefore, implantation won't occur.  Estrogen can have toxic side effects, however, so this treatment is  discouraged. Unless you really want to breed your cat, I recommend  annotations.