Editing Neutering (section)

==Health and behavioral effects==
{{procon|date=April 2017}}
{{see also|Castration#Medical consequences}}

===Advantages===
Besides being a birth control method, and being convenient to many owners, castrating/spaying has the following health benefits:
* [[Sexual dimorphism|Sexually dimorphic]] behaviors such as [[copulation|mounting]] and [[urine spraying]] are reduced due to the decrease in hormone levels brought about by neutering.  In species other than dogs, certain forms of male [[aggression]] are also reduced.<ref>{{cite journal |last1=Farhoody |first1=Parvene |title=Aggression toward Familiar People, Strangers, and Conspecifics in Gonadectomized and Intact Dogs |journal=Frontiers in Veterinary Science |date=26 February 2018 |volume=5 |page=18 |doi=10.3389/fvets.2018.00018 |pmid=29536014 |pmc=5834763 |doi-access=free }}</ref>  Sexual behavior in cats seems to make them especially undesirable to pet owners.<ref name="Kustritz">{{cite journal |title=Determining the Optimal age for Gonadectomy of Dogs and Cats | doi=10.2460/javma.231.11.1665 |date= 2007 |last1= Kustritz |first1= Margaret V. Root |journal= Journal of the American Veterinary Medical Association |volume= 231 |issue= 11 |pages= 1665–75 |pmid= 18052800| s2cid=4651194 | url=https://semanticscholar.org/paper/0d15d47bace395843f23fc8eef127dcbfc22bf82 |doi-access= free }}</ref>
* 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.<ref>{{cite web|last1=Poulton|first1=Gerry|title=Mammary Tumours in Dogs|url=http://www.vef.unizg.hr/org/kirurgija/wp-content/uploads/2010/04/CESA_January_2009.pdf.pdf|publisher=Irish Veterinary Journal|url-status=live|archive-url=https://web.archive.org/web/20150402120904/http://www.vef.unizg.hr/org/kirurgija/wp-content/uploads/2010/04/CESA_January_2009.pdf.pdf|archive-date=2 April 2015}}</ref>
* Neutering increases life expectancy in cats: one study found castrated male cats live twice as long as intact males, while spayed female cats live 39% longer than intact females.<ref> [https://www.humanesociety.org/resources/why-you-should-spayneuter-your-pet The Humane Society of the United States]</ref> Non-neutered cats in the U.S. are three times more likely to require treatment for an animal bite. Having a cat neutered confers health benefits, because castrated males cannot develop testicular cancer, spayed females cannot develop uterine, cervical or ovarian cancer, and both have a reduced risk of mammary cancer.{{Citation needed|date=February 2023}}
* Without the ability to reproduce, a female necessarily has zero risk of pregnancy complications, such as [[Metrorrhagia|spotting]] and [[false pregnancy]], the latter of which can occur in more than 50% of unspayed female dogs.<ref>{{cite web |url=http://www.ivis.org/advances/concannon/gobello/ivis.pdf |title=Canine Pseudopregnancy: A Review |first=C. |last=Gobello |date=23 August 2001 |work=IVIS.org |publisher=International Veterinary Information Service |access-date=13 April 2010 |display-authors=etal |url-status=dead |archive-url=https://web.archive.org/web/20110419121323/http://www.ivis.org/advances/concannon/gobello/ivis.pdf |archive-date=19 April 2011  }}</ref>
* [[Pyometra]], [[endometrial cancer|uterine cancer]], [[ovarian cancer]], and [[testicular cancer]] are prevented, as the susceptible organs are removed, though [[Pyometra#Stump pyometra|stump pyometra]] may still occur in spayed females.
* Pyometra (or a pus filled womb) ('Pyo' = pus; 'metra' = uterus or womb) is a life-threatening condition that requires emergency veterinary treatment. The risk of a non-spayed female dog developing pyometra by age 10 is 25% across all breeds, but can be as high as 54% in some breeds.<ref>{{cite journal|title=Breed Risk of Pyometra in Insured Dogs in Sweden|journal=Journal of Veterinary Internal Medicine| doi=10.1111/j.1939-1676.2001.tb01587.x|volume=15|issue=6|pages=530–538|year=2001|last1=Egenvall|first1=Agneta|last2=Hagman|first2=Ragnvi|last3=Bonnett|first3=Brenda N.|last4=Hedhammar|first4=Ake|last5=Olson|first5=Pekka|last6=Lagerstedt|first6=Anne-Sofie|pmid=11817057|doi-access=}}</ref> The treatment of choice for a closed-pyometra (where the cervix is closed and the pus cannot drain) is admission to hospital, commencement on intravenous fluids and appropriate antibiotics and, once stable enough for the anaesthetic and surgery, emergency removal of the infected pus-filled uterus. Medical management can be attempted if the animal's condition allows (for example in the case of an 'open' pyometra where the pus drains per-vaginum from the uterus via the open cervix) or dictates (where the animal is too old or otherwise unwell to withstand surgery), if the owner wishes to keep the dog entire to breed or if the owner is unable to afford the veterinary fees associated with surgery. Emergency removal of the infected uterus carries a much higher degree of risk of death than a routine 'spay' operation. The risk of death from in dogs undergoing surgical treatment for pyometra is up to 17%.<ref>{{cite journal|title=Results and complications of surgical treatment of pyometra: a review of 80 cases|journal=[[Journal of the American Animal Hospital Association]]|url=http://cel.webofknowledge.com/InboundService.do?product=CEL&SID=T2VUDVHmOxrj332hibj&UT=WOS%3AA1989AR48200015&SrcApp=Highwire&action=retrieve&Init=Yes&SrcAuth=Highwire&Func=Frame&customersID=Highwire&IsProductCode=Yes&mode=FullRecord|archive-url=https://archive.today/20150319014740/http://cel.webofknowledge.com/InboundService.do?product=CEL&SID=T2VUDVHmOxrj332hibj&UT=WOS:A1989AR48200015&SrcApp=Highwire&action=retrieve&Init=Yes&SrcAuth=Highwire&Func=Frame&customersID=Highwire&IsProductCode=Yes&mode=FullRecord|url-status=dead|archive-date=2015-03-19}}</ref> Thus the risk of death in entire female dogs from a pyometra, even if given correct veterinary attention can be up to 9% by 10 years of age (17% of 54%). This risk is reduced to virtually zero if spayed.

===Disadvantages===
* As with any surgical procedure, immediate complications of neutering include the usual [[Veterinary anesthesia|anesthetic]] and [[Veterinary surgery|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.<ref>{{Cite journal|pmid=18466167 |date=2008 |author1=Brodbelt |first2=K. J. |first3=R. A. |first4=P. J. |first5=L. E. |first6=D. U. |first7=J. L. |title=The risk of death: the confidential enquiry into perioperative small animal fatalities |volume=35 |issue=5 |pages=365–73 |doi=10.1111/j.1467-2995.2008.00397.x |journal=Veterinary Anaesthesia and Analgesia |last2=Blissitt |last3=Hammond |last4=Neath |last5=Young |last6=Pfeiffer |last7=Wood|s2cid=22017193 |url=https://researchonline.rvc.ac.uk/id/eprint/1370/1/1370.pdf }}</ref>
* Spaying and castrating cats and dogs may increase the risk of [[obesity]] if nutritional intake is not reduced to reflect the lower metabolic requirements of neutered animals.<ref name="PMID18774325">{{cite journal | pmid = 18774325 | doi=10.1016/j.jfms.2008.07.002 | volume=11 | issue=2 | title=Prevalence and risk factors of obesity in an urban population of healthy cats |date=February 2009 | journal=Journal of Feline Medicine and Surgery | pages=135–40 | author=Colliard L. | author2=Paragon B. M. | author3=Lemuet B.| author4=Bénet J. J. | author5=Blanchard G.| s2cid=25617418 | doi-access=free | pmc=10832791 }}</ref> In cats, a decrease in sex hormone levels seems to be associated with an increase in food intake.<ref name="PMID17845247">{{cite journal | pmid = 17845247 | doi=10.1111/j.1439-0396.2006.00667.x | volume=91 | issue=9–10 | title=Oestradiol, but not genistein, inhibits the rise in food intake following gonadectomy in cats, but genistein is associated with an increase in lean body mass |date=October 2007 | journal=Journal of Animal Physiology and Animal Nutrition | pages=400–10 | author=Cave N. J. | author2=Backus R. C. | author3=Marks S. L.| author4=Klasing K. C.}}</ref> In dogs, the effects of neutering as a risk factor for obesity vary among breeds.<ref name="PMID15923551">{{cite journal | pmid = 15923551 | volume=156 | issue=22 | title=Prevalence of obesity in dogs examined by Australian veterinary practices and the risk factors involved |date=May 2005 | journal=Veterinary Record | pages=695–702 | author=McGreevy P. D. | author2=Thomson P. C. | author3=Pride C.| author4=Fawcett A. | author5=Grassi T.| author6=Jones B. | doi=10.1136/vr.156.22.695| s2cid=36725298 }}</ref>
* Neutered dogs of both sexes are at a twofold excess risk to develop [[osteosarcoma]] (bone cancer) as compared to intact dogs. The risk of osteosarcoma increases with increasing breed size and especially height.<ref name=Priester>{{Cite journal|pmid=7254313 |date=1980 |author1=Priester |first2=F. W. |title=The Occurrence of Tumors in Domestic Animals |issue=54 |pages=1–210 |journal=National Cancer Institute Monograph |last2=McKay}}</ref><ref name=Ru>{{Cite journal|doi=10.1016/S1090-0233(98)80059-2 |title=Host related risk factors for canine osteosarcoma |date=1998 |last1=Ru |first1=G. |first2=B. |first3=L. |journal=The Veterinary Journal |volume=156 |pages=31–9 |pmid=9691849 |issue=1 |last2=Terracini |last3=Glickman}}</ref><ref name=Cooley>{{Cite journal|author=Cooley, D. M.|author2=Beranek, B. C.|date=1 November 2002|title=Endogenous gonadal hormone exposure and bone sarcoma risk|journal=Cancer Epidemiology, Biomarkers & Prevention|url=http://cebp.aacrjournals.org/cgi/content/full/11/11/1434|pmid=12433723|volume=11|issue=11|pages=1434–40|display-authors=etal|url-status=live|archive-url=https://web.archive.org/web/20030825175957/http://cebp.aacrjournals.org/cgi/content/full/11/11/1434|archive-date=25 August 2003}}</ref>
* 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.<ref name=Prymak>{{Cite journal |author=Prymak C. |author2=McKee L. J. |author3=Goldschmidt M. H.|author4=Glickman L. T. |date=1988 |title=Epidemiologic, clinical, pathologic, and prognostic characteristics of splenic hemangiosarcoma and splenic hematoma in dogs: 217 cases (1985) |journal= Journal of the American Veterinary Medical Association |volume=193 |issue=6 |pages=706–712 |doi=10.2460/javma.1988.193.06.706 |pmid=3192450}}</ref><ref name=Ware>{{Cite journal|doi=10.1892/0891-6640(1999)013<0095:CTID>2.3.CO;2 |pmid=10225598 |title=Cardiac Tumors in Dogs: 1982–1995 |date=1999 |last1=Ware |first1=Wendy A. |last2=Hopper |first2=David L. |journal=Journal of Veterinary Internal Medicine |volume=13 |issue=2 |pages=95–103|doi-broken-date=4 January 2025 }}</ref>
* Spaying and castrating is associated with an increase in urinary tract cancers in dogs, however the risk is still less than 1%.<ref name=Sanborn>{{cite web |author=Sanborn, L. J. |title=Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs |url=http://www.naiaonline.org/pdfs/LongTermHealthEffectsOfSpayNeuterInDogs.pdf |date=14 May 2007 |access-date=13 April 2010 |url-status=live |archive-url=https://web.archive.org/web/20100107141430/http://www.naiaonline.org/pdfs/longtermhealtheffectsofspayneuterindogs.pdf |archive-date=7 January 2010  }}</ref>
* Neutered dogs of both sexes have a 27% to 38% increased risk of adverse reactions to vaccinations. However, the incidence of adverse reactions for neutered and intact dogs combined is only 0.32%.<ref name=Moore>{{Cite journal |author=Moore G. E. |author2=Guptill L. F. |author3=Ward M. P.|author4=Glickman N. W. |author5=Faunt K. F.|author6=Lewis H. B. |author7=Glickman L.T. |date=2005 |title=Adverse events diagnosed within three days of vaccine administration in dogs|journal= Journal of the American Veterinary Medical Association |volume=227 |issue=7 |pages=1102–1108 |doi=10.2460/javma.2005.227.1102 |pmid=16220670|s2cid=8625559 |doi-access=free }}</ref>
* Neutered dogs have been known to develop hormone-responsive [[alopecia]] (hair loss).<ref>{{Cite web|url=https://m.petmd.com/dog/conditions/endocrine/c_dg_hormone_responsive_dermatoses|title=Baldness and Hormone-Related Skin Disorders in Dogs|website=m.petmd.com|access-date=2019-12-28}}</ref>
* A 2004 study found that neutered dogs had a higher incidence of cranial cruciate ligament (CCL) rupture, a form of anterior cruciate ligament (ACL) injury.<ref>{{cite journal |last1=Slauterbeck |first1=J. R. |author2=Pankratz, K. |author3=Xu, K. T. |author4=Bozeman, S. C. |author5= Hardy, D. M.  |title=Canine Ovariohysterectomy and Orchiectomy Increases the Prevalence of ACL Injury |journal=Clinical Orthopaedics and Related Research |date=Dec 2004 |volume=429 |issue=429 |pages=301–5|doi=10.1097/01.blo.0000146469.08655.e2 |pmid=15577502 |s2cid=23047078 }}</ref>
* A study of [[golden retrievers]] found that castrated males were 3 times more likely than intact males to be diagnosed with [[lymphoma in animals|lymphoma]] and 2 times more likely to have [[Hip dysplasia (canine)|hip dysplasia]].<ref>{{cite journal|last=Torres de la Riva|first=Gretel|title=Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers|doi=10.1371/journal.pone.0055937|pmid=23418479|pmc=3572183|journal=PLOS ONE|volume=8|issue=2|pages=e55937|year=2013|bibcode=2013PLoSO...855937T|doi-access=free}}</ref>
* Castration and spaying can increase the risk of geriatric cognitive impairment.<ref name=Sanborn />
* About 2% of castrated [[male dogs]] eventually develop [[prostate cancer]], compared to less than 0.6% of intact males.<ref name=Teske>{{Cite journal|doi=10.1016/S0303-7207(02)00261-7 |title=Canine prostate carcinoma: epidemiological evidence of an increased risk in castrated dogs |date=2002 |last1=Teske |first1=E. |journal=Molecular and Cellular Endocrinology |volume=197 |pages=251–5 |pmid=12431819 |first2=E. C. |first3=E. M. |first4=E. |first5=J. A. |issue=1–2 |last2=Naan |last3=Van Dijk |last4=Van Garderen |last5=Schalken|s2cid=7080561 }}</ref><ref name=Sorenmo>{{Cite journal|doi=10.1046/j.1476-5829.2003.00007.x |title=Immunohistochemical characterization of canine prostatic carcinoma and correlation with castration status and castration time |date=2003 |last1=Sorenmo |first1=K. U. |first2=M. |first3=F. |first4=C. |first5=J. |journal=Veterinary and Comparative Oncology |volume=1 |pages=48–56 |pmid=19379330 |issue=1 |last2=Goldschmidt |last3=Shofer |last4=Goldkamp |last5=Ferracone}}</ref> The evidence is most conclusive for [[Bouvier des Flandres|Bouviers]].<ref name=Sanborn/>
* In a study of 29 intact male dogs and 47 castrated males aged 11–14, the neutered males were significantly more likely to progress from one geriatric cognitive impairment condition (out of the four conditions – disorientation in the house or outdoors, changes in social interactions with human family members, loss of house training, and changes in the sleep-wake cycle) to two or more conditions. Testosterone in intact males is thought to slow the progression of cognitive impairment, at least in dogs that already have mild impairment.<ref>{{Cite journal|pmid=11439769 |doi=10.2460/javma.2001.219.51 |date=2001 |author1=Hart |title=Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs |volume=219 |issue=1 |pages=51–6 |journal=Journal of the American Veterinary Medical Association|s2cid=17565731 |doi-access=free }}</ref>
* As compared to intact males, castrated cats are at an increased risk for certain problems associated with [[feline lower urinary tract disease]]. They are much more likely to suffer from [[feline cystitis]] which can escalate into a life-threatening urethral blockage.<ref>{{Cite journal|pmid=11345305 |doi=10.2460/javma.2001.218.1429 |date=2001 |author1=Lekcharoensuk |first2=C. A. |first3=J. P. |title=Epidemiologic study of risk factors for lower urinary tract diseases in cats |volume=218 |issue=9 |pages=1429–35 |journal=Journal of the American Veterinary Medical Association |last2=Osborne |last3=Lulich|doi-access=free }}</ref>
* Neutering has been associated with an increased likelihood of urethral sphincter incontinence in male dogs.<ref>{{cite journal | last1 = Aaron | first1 = A. | last2 = Eggleton | first2 = K. | last3 = Power | first3 = C. | last4 = Holt | first4 = P. E. | title = Urethral sphincter mechanism incompetence in male dogs: a retrospective analysis of 54 cases | journal = Veterinary Record | volume = 139 | issue = 22 | pages= 542–6| year = 1996 | doi=10.1136/vr.139.22.542| pmid = 8961524 | s2cid = 5642622 }}</ref>
* There is evidence that spaying can increase the risk of [[urinary incontinence]] in dogs, especially when done before the age of three months. Up until 12 months of age, the risk decreases as the age at spaying increases.<ref name="Beauvais">{{Cite journal | last1 = Beauvais | first1 = W. | last2 = Cardwell | first2 = J. M. | last3 = Brodbelt | first3 = D. C. | doi = 10.1111/j.1748-5827.2011.01176.x | title = The effect of neutering on the risk of urinary incontinence in bitches - a systematic review | journal = Journal of Small Animal Practice | volume = 53 | issue = 4 | pages = 198–204 | year = 2012 | pmid =  22353203| url = https://animalstudiesrepository.org/cgi/viewcontent.cgi?article=1002&context=endoc }}</ref><ref>{{Cite web|url=https://www.merck-animal-health-usa.com/dp/49|title=Merck Animal Health USA|website=www.merck-animal-health-usa.com|access-date=2019-12-14}}</ref>
* Spayed female dogs are at an increased risk of [[hypothyroidism]].<ref name=Panciera>{{Cite journal |author=Panciera D. L. |date=1994 |title=Hypothyroidism in dogs: 66 cases (1987–1992) |journal= Journal of the American Veterinary Medical Association |volume=204 |issue=5 |pages=761–767|doi=10.2460/javma.1994.204.05.761 |pmid=8175472 }}</ref>

===Current research===
Various studies of the effects neutering has overall on male and female dog aggression have been unable to arrive at a consensus. A possible reason for this according to two studies is changes to [[Dog aggression#Factors contributing to aggression|other factors]] have more of an effect than neutering.<ref>{{Cite journal|author=Kobelt A. J.|author2=Hemsworth P. H.|author3=Barnett J. L.|author4=Coleman G. J. |title=A survey of dog ownership in suburban Australia-conditions and behaviour problems |journal=Applied Animal Behaviour Science |date=2003 |volume=82 |pages=137–148 |doi=10.1016/S0168-1591(03)00062-5|issue=2}}</ref><ref name="Casey">{{Cite journal|author=Casey R. A.|author2=Loftus B.|author3=Bolster C.|author4=Richards G. J.|author5=Blackwell E. J. |title=Human directed aggression in domestic dogs (Canis familiaris): Occurrence in different contexts and risk factors |journal=Applied Animal Behaviour Science |date=March 2014  | volume=152 |pages=52–63 |doi=10.1016/j.applanim.2013.12.003|hdl=10983/14199|hdl-access=free}}</ref> One study reported results of aggression towards familiar and strange people and other dogs reduced between 10 and 60 percent of cases,<ref>[http://www.associationofanimalbehaviorprofessionals.com/effects_of_neutering.html The Effects of Spaying and Neutering on Canine Behavior] {{webarchive|url=https://web.archive.org/web/20141022175541/http://www.associationofanimalbehaviorprofessionals.com/effects_of_neutering.html |date=22 October 2014 }} James O’Heare, Association of Animal Behavior Professionals</ref> while other studies reported increases in possessive aggression<ref>{{Cite journal|author=Guy N. C.|author2=Luescher U. A.|author3=Dohoo S. E.|author4=Spangler E.|author5=Miller J. B|author6=Dohoo I. R.|author7=Bate L. A. |title=A case series of biting dogs: characteristics of the dogs, their behaviour, and their victims |journal=Applied Animal Behaviour Science |date=2001 |volume=74 |pages=15–57 |doi=10.1016/S0168-1591(01)00155-1}}</ref> and aggression towards familiar and strange people,<ref name="Takeuchi">{{Cite journal|author=Takeuchi Y.|author2= Ogata N.|author3=Houpt J. A.|author4=Scarlett J. M. |title=Differences in background and outcome of three behavior problems of dogs |journal=Applied Animal Behaviour Science |date=2001 |volume=70 |pages=297–308 |doi=10.1016/S0168-1591(00)00156-8 |pmid=11179553 |issue=4}}</ref> and more studies reported there was no significant difference in aggression risk between neutered and non-neutered males.<ref name="Casey"/><ref>{{Cite journal|author=Neilson J.|author2=Eckstein R.|author3=Hart B. |title=Effects on castration on problem behaviors in male dogs with reference to age and duration of behavior |journal=Journal of the American Veterinary Medical Association |date=1997 |volume=211 |issue=2 |pages=180–182 |doi=10.2460/javma.1997.211.02.180 |pmid=9227747}}</ref> For females with existing aggression, many studies reported increases in aggressive behavior<ref name="Polsky">{{Cite journal|author=Polsky R. H. |title=Recognizing dominance aggression in dogs |journal=Veterinary Medicine |date=1996 |volume=91 |pages=196–201}}</ref><ref name="Blackshaw">{{Cite journal|author=Blackshaw, J.K. |title=An overview of types of aggressive behavior in dogs and methods of treatment |journal=Applied Animal Behaviour Science |date=1991 |volume=30 |pages=351–361 |doi=10.1016/0168-1591(91)90140-S|issue=3–4}}</ref><ref name="Wright">{{Cite journal|author=Wright J. C. |title=Canine aggression toward people. Bite scenarios and prevention |journal=Veterinary Clinics of North America: Small Animal Practice |date=1991 |volume=21 |issue=2 |pages=299–314 |pmid=2053252 |doi=10.1016/s0195-5616(91)50034-6}}</ref><ref name="Crowell">{{Cite journal|author=Crowell-Davis S. L. |title=Identifying and correcting human-directed dominance aggression of dogs |journal=Veterinary Medicine |date=1991 |volume=86 |pages=990–998}}</ref> and some found increased separation anxiety behavior.<ref name="Takeuchi"/><ref>{{Cite journal|author=Podberscek A. L.|author2=Serpell J. A. |title=The English Cocker Spaniel: preliminary findings on aggressive behaviour |journal=Applied Animal Behaviour Science |date=1996 |volume=47 |issue=1–2 |pages=75–89 |doi=10.1016/0168-1591(95)01012-2}}</ref> A report from the American Kennel Club Canine Health Foundation reported significantly more behavioral problems in castrated dogs. The most commonly observed behavioral problem in spayed females was fearful behavior and the most common problem in males was aggression.<ref>Meuten D. J. ''Tumors in Domestic Animals''. 4th Edn. Iowa State Press, Blackwell Publishing Company, Ames, Iowa, p. 575</ref> Early age gonadectomy is associated with an increased incidence of noise phobias and {{clarify span|undesirable sexual behaviors|date=September 2013}}.<ref>{{cite journal | author = Spain C. V. | author2 = Scarlett J. M. | author3 = Houpt K. A. | date = 2004 | title = Long-term risks and benefits of early-age gonadectomy in dogs | journal = Journal of the American Veterinary Medical Association | volume = 224 | issue = 3| pages = 380–387 | doi = 10.2460/javma.2004.224.380 | pmid = 14765797 | s2cid = 11696126 | doi-access = free }}</ref>