Sterilization (surgical procedure)

Sterilization or Sterilisation is a surgical technique leaving a male or female unable to procreate. It is a method of birth control. For non-surgical causes of sterility, see infertility.

Common sterilization methods include:
 * Vasectomy in males. The vasa deferentia, the tubes which connect the testicles to the prostate, are cut and closed. This prevents sperm produced in the testicles to enter the ejaculated semen (which is mostly produced in the seminal vesicles and prostate). Although the term vasectomy is established in the general community, the correct medical terminology is deferentectomy, since the structure known as the vas deferens has been renamed the ductus deferens.
 * Tubal ligation in females, known popularly as "having one's tubes tied". The Fallopian tubes, which allow the sperm to fertilize the ovum and would carry the fertilized ovum to the uterus, are closed. This generally involves a general anaethetic and a laparotomy or laparoscopic approach to cut, clip or cauterize the fallopian tubes. Less commonly used is the Essure office procedure of inducing scarring and occlusion of the tubes by the effects of micro-inserts placed by a catheter passed through the cervix and uterus.
 * Hysterectomy in females. The uterus is surgically removed, permanently preventing pregnancy and some diseases, such as uterine cancer.
 * Castration in males. The testicles are surgically removed. This is frequently used for the sterilization of animals, with added effects such as docility, greatly reduced sexual behaviour, and faster weight gain (which is desirable in some cases, for example to accelerate meat production).

Sterilization of animals
In animals, castration (removal of the testes) and salpingo-oophorectomy (removal of the ovaries and fallopian tubes), called "neutering" or "spaying" when applied to pets, are used to reduce or eliminate sexual behaviour, and to prevent conception, heat and possible uterine diseases in females, potentially prolonging a female animal's lifespan. The impact on the long-term health of a neutered male is more negative. Due to the hormonal changes involved with both genders, this will definitely cause minor behavioral changes in the animal. When these changes are undesired, a different method of sterilization can be used, such as vasectomy in males or tubal ligation in females. A typical example of this practise is when male cats are subjected to vasectomy so that they are able to mate with females, thereby "bringing them off heat" (terminating estrus). This keeps the condition of the female from deteriorating due to the extra energy that is expended during estrus. A vasectomized male cat is called a "teaser tom" by cat breeders.

Animal control organizations urge owners who do not keep animals for the specific purpose of breeding to have their pets spayed or neutered in order to prevent an increase in the population of stray animals. Such stray animals are often malnourished, and are frequently euthanized by animal welfare societies.