question: If neutering or spaying an animal is necessary to prevent unwanted babies, why not just give them a hysterectomy or vasectomy instead? Do the remaining hormones still have other negative effects?
comment: Spaying a female animal IS a hysterectomy - the uterus is removed. Yes, the hormones are a reason for neutering male animals. Testosterone can cause aggressive, territorial behaviour such as fighting and spray-marking, or wandering in search of females.
passages: Section::::AVMA policy on pediatric spay/neuter.
  
  The American Veterinary Medical Association issued a policy on Early-Age (Prepubertal) Spay/Neuter of Dogs and Cats in 1994. It was revised by the AVMA Executive Board April 1999 and April 2004 and now reads as follows:
  
  Although it is desirable to spay/neuter early for population control, there has been considerable concern from the veterinary community over these practices that have not been validated by substantial third party study of the long term outcomes. They revised their recommendation in 2017 to extend the feline spay age.
  
  Section::::Anesthesia and surgical considerations.
   It was once believed that female cats and dogs should not be spayed until the animal delivered one litter or, at least, experienced one estrus or “heat” cycle. (There was little concern about neutering males, other than for behavioral reasons, since males do not get pregnant.) Research in the 1960s proved that female animals permitted to reach sexual maturity prior to being spayed were susceptible to a higher risk of mammary cancer than those animals spayed prior to their first cycle. As a result, the recommendation was revised to perform surgeries just prior to the average anticipated age for the first cycle, 4 to 6 months for cats and 6 to 12 months for dogs.
   Section::::Research on non-surgical sterilization/contraception.:Hormone agonists and antagonists.
  
  Many GnRH agonists similar to Suprelorin® have been developed for human use. When given as long-acting implants, these cause “medical castration,” that is, the complete suppression of reproductive activity and the suppression of sex steroids. They have been shown to be effective in both dogs and cats. 
   Compounds that bind and block the GnRH receptor can also cause suppression of fertility and sex steroids. Compounds such as cetrorelix and ganorelix have been shown to cause short-term fertility suppression in dogs. None of these compounds, however, have been developed for this use, likely due to the high cost of manufacture.
  
  Treatment with Müllerian inhibiting hormone (MIH) can cause regression of follicles and result in suppression of fertility in female animals.
  
  Section::::Research on non-surgical sterilization/contraception.:Targeted delivery of cytotoxins.
   Section::::Health and behavioral effects.:Disadvantages.
  
  Section::::Health and behavioral effects.:Disadvantages.:General.
  
  BULLET::::- As with any surgical procedure, immediate complications of neutering include the usual anesthetic and surgical complications, such as bleeding, infection, and death. These risks are relatively low in routine neutering; however, they may be increased for some animals due to other pre-existing health factors. In one study the risk of anesthetic-related death (not limited to neutering procedures) was estimated at 0.05% for healthy dogs and 0.11% for healthy cats. The risks for sick animals were 1.33% for dogs and 1.40% for cats.
   Non-surgical fertility control for dogs and cats
  
  Non-surgical fertility control is the prevention of reproduction without the use of surgery. The most common form of sterilization in dogs and cats is surgical, spaying in females and castration in males. Non-surgical fertility control can either result in sterilization or temporary contraception and could offer a cheaper way to keep wild dog and cat populations under control. As of 2019, only contraceptives are commercially available. Research is ongoing into methods that could result in permanent suppression of fertility.
  
  Section::::Background.
   As of 2013, an estimated 75% of 700 million dogs worldwide were free to roam and reproduce, resulting in overpopulation, high mortality rates and poor health. The main management approach is surgical sterilization, i.e. the removal of testes or ovaries, often performed through trap-neuter-return strategies. However this approach requires significant resources, including appropriate facilities. If successful, non-surgical approaches may be a more humane, economic and time-efficient option, although no effective permanent treatment is yet available.
   Section::::Research on non-surgical sterilization/contraception.:Gene delivery.
   BULLET::::- Zeuterin™, formerly known as EsterilSol™ and Neutersol™, received approval from the U.S. Food and Drug Administration (FDA) in 2014 for permanent sterilization of male dogs. It is also approved for use in Mexico, Colombia, Bolivia, Panama, and Turkey. It was administered as an injection as a single dose in each testicle. It is not currently commercially available.
   Tubal ligation: Snipping and tying of fallopian tubes as a sterilization measure can be performed on female cats, dogs, and other species; it is essentially the female equivalent of vasectomy, but a more invasive procedure. Risk of unwanted pregnancies is insignificantly small. Only a few veterinarians perform the procedure.
   BULLET::::- There is some weak evidence that spaying can increase the risk of urinary incontinence in dogs, especially when done before the age of three months. Up till 12 months of age, the risk decreases as the age at spaying increases.
  
  BULLET::::- Spayed female dogs are at an increased risk of hypothyroidism.
  
  Section::::Health and behavioral effects.:Current research.
   Like other forms of neutering, vasectomy and tubal ligation eliminate the ability to produce offspring. They differ from neutering in that they leave the animal's levels and patterns of sex hormone unchanged. Both sexes will retain their normal reproductive behavior, and other than birth control, none of the advantages and disadvantages listed above apply. This method is favored by some people who seek minimal infringement on the natural state of companion animals to achieve the desired reduction of unwanted births of cats and dogs.
   BULLET::::- Studies of cardiac tumors in dogs showed that there was a 5 times greater risk of hemangiosarcoma (cancer of blood vessel lining), one of the three most common cancers in dogs, in spayed females than intact females and a 2.4 times greater risk of hemangiosarcoma in castrated dogs as compared to intact males.
  
  BULLET::::- Spaying and castrating is associated with an increase in urinary tract cancers in dogs, however the risk is still less than 1%.
   BULLET::::- Without the ability to reproduce, a female necessarily has zero risk of pregnancy complications, such as spotting and false pregnancy, the latter of which can occur in more than 50% of unspayed female dogs.
  
  BULLET::::- Pyometra, uterine cancer, ovarian cancer, and testicular cancer are prevented, as the susceptible organs are removed, though stump pyometra may still occur in spayed females.
   Neutering or spaying, which involves removing some of the reproductive organs, is often carried out as a method of birth control in household pets. Many animal shelters require these procedures as part of adoption agreements. In large animals the surgery is known as castration.
  
  Birth control is also being considered as an alternative to hunting as a means of controlling overpopulation in wild animals. Contraceptive vaccines have been found to be effective in a number of different animal populations. Kenyan goat herders fix a skirt, called an olor, to male goats to prevent them from impregnating female goats.
  
  Section::::Further reading.
   While the age-unrelated risks and benefits cited above also apply to early-age neutering, various studies have indicated that the procedure is safe and not associated with increased mortality or serious health and behavioral problems when compared to conventional age neutering. Anesthesia recovery in young animals is usually more rapid and there are fewer complications. One study found that in female dogs there is an increasing risk of urinary incontinence the earlier the procedure is carried out; the study recommended that female dogs be spayed no earlier than 3 to 4 months of age. A later study comparing female dogs spayed between 4 and 6 months and after 6 months showed no increased risk.
   Section::::Reproductive health.:Spaying and neutering.
  
  Spaying (females) and neutering (males) refers to the sterilization of animals, usually by removal of the male's testicles or the female's ovaries and uterus, in order to eliminate the ability to procreate, and reduce sex drive. Neutering has also been known to reduce aggression in male dogs, but has been shown to occasionally increase aggression in female dogs.
  
  Animal control agencies in the United States and the ASPCA advise that dogs not intended for further breeding should be spayed or neutered so that they do not have undesired puppies.
   Early-age neutering, also known as pediatric spaying or prepubertal gonadectomy, is the removal of the ovaries or testes before the onset of puberty. It is used mainly in animal sheltering and rescue where puppies and kittens can be neutered before being adopted out, eliminating non-compliance with sterilization agreement, which is typically above 40%. The American Veterinary Medical Association, American Animal Hospital Association and the Canadian Veterinary Medical Association support the procedure for population control, provided that the veterinarian uses his/her best knowledge when making the decision about the age at neutering.
   Pediatric spaying
  
  Pediatric spaying (also known as “prepuberal” or “early” spaying) or neutering is defined as performing an ovariohysterectomy (spaying) or orchidectomy (castration or neutering) on a kitten or puppy between the ages of 6 and 14 weeks. Spaying and neutering are sterilization procedures which prevent the animals from reproducing. The procedures are also referred to as “gonadectomies” in the veterinary literature.
  
  Section::::Background.
   BULLET::::3. While external sexual organs of the animals who were sterilized at a younger age did not mature fully or to the same extent of those sterilized later, there was no significant negative impact on urinary tract health for most animals. Male cats sterilized at a younger age experienced a lower rate of urinary tract blockage than male cats sterilized at an older age. The one significant cause for concern in the studies was an increased incidence of urinary incontinence in female dogs leading to recommendations to delay spaying female dogs until 3 months of age when there is no concern about non-compliance with spay policies.
   Neutering is usually performed to prevent breeding, prevent unwanted behavior, or decrease risk of future medical problems. Neutering is also performed as an emergency procedure to treat certain reproductive diseases, like pyometra and testicular torsion, and it is used to treat ovarian, uterine, and testicular cancer. It is also recommended in cases of cryptorchidism to prevent torsion and malignant transformation of the testicles. Please see spaying and neutering for more information on the advantages and disadvantages of this procedure.
   Research into gonadotropin-releasing hormone (GnRH) as a treatment for men with prostate cancer subsequently led to its consideration as a fertility inhibitor for dogs. GnRH inhibits sex hormones like estrogen and testosterone, inhibiting ovulation and sperm production. 
  
  Section::::Available products.
  
  There are a limited number of non-surgical fertility control options available for cats and dogs, which vary in effectiveness, duration of action and safety.
  
  BULLET::::- Progestin contraceptives are approved for contraception in male and female dogs and cats in multiple countries. Typically approval is for a few months of use.
   Spaying in female dogs removes the production of progesterone, which is a natural calming hormone and a serotonin uplifter. Spaying may therefore escalate any observable aggressive behaviour, either to humans or other dogs.
  
  The risk of infections, bleeding, ruptures, inflammation and reactions to the drugs given to the animal as part of the procedure are all possibilities that should be considered.
  
  Section::::Methods of sterilization.:Males (castration).
   The second study from 2014 highlighted significant difference in closely related breeds (retrievers), suggesting that inter-breed variability is quite high and that sweeping legal measures and surgical mandates are not the best solutions to canine welfare and health. Specifically the study states: "In Labrador Retrievers, where about 5 percent of gonadally intact males and females had one or more joint disorders, neutering at 6 months doubled the incidence of one or more joint disorders in both sexes. In male and female Golden Retrievers, with the same 5 percent rate of joint disorders in intact dogs, neutering at 6 months increased the incidence of a joint disorder to 4–5 times that of intact dogs. The incidence of one or more cancers in female Labrador
   BULLET::::- Early spaying significantly reduces the risk of development of mammary tumours in female dogs. The incidence of mammary tumours in un-spayed female dogs is 71% (of which approximately 50% will be malignant and 50% will be benign), but if a dog is spayed before its first heat cycle, the risk of developing a mammary tumour is reduced to 0.35%—a 99.5% reduction. The positive effects of spaying on reduction of later mammary tumours decreases with each heat the dog has (backing up the contention that the greatest benefit to reduce future mammary tumour development is to spay before the first heat), and there is no added benefit to spaying to reduce recurrence of a mammary tumour once it has been diagnosed.
  
presuppositions: Spaying an animal is different from a hysterectomy. Spaying is distinct from a hysterectomy.
corrections: Spaying an animal is a hysterectomy. Spaying is the same as a hysterectomy.
raw_presuppositions: Spaying an animal is different from a hysterectomy. Spaying is distinct from a hysterectomy.
raw_corrections: Spaying an animal is a hysterectomy. Spaying is the same as a hysterectomy.