Spay and Neuter References

Over the years the once sacred dogma of routine pre-adult mass spay and neuter for companion animals has come under increased scrutiny from multiple sources. As so often happens in animal-related issues, this has generated a lot of passion. And as also often occurs, those who represent the extremes make the most noise in their attempts to gain disciples for their respective views. Neither the passion nor the extremism does anything to help the average pet owner or animal care professional who wants to become more informed about the issue.

Below is a collection of resources I’ve put together over the years that explore some of the many aspects of gonad removal, its benefits and costs. The bottom line is that there is no universal right answer. Blanket spay and neuter policies that work for shelters may not work for individuals for whom the health and welfare of their individual animals is the primary concern. Where problems arise is when one organization or individual makes choices that benefit them and expect others to assume the responsibility for any costs associated with that choice.

To suggest additional resources, please e-mail

  • General Background Information
  • Historic Background Information
  • Medical Studies and Articles
  • Behavioral Studies and Articles
  • Additional Online Sources

General background information: 

  • Kass, Phillip. (2000) Understanding Animal Companion Surplus in the United States Relinguishment of Nonadoptables to Animal shelters for Euthanasia, Journal of Applied Animal Welfare Science. 4(4), pp 237-248.
  • Niehoff, Debra. (1999) The Biology of Violence (New York: Free Press). The entire book provides as excellent overview of the highly complex relationship between physiology and behavior. Chapter Six, “Raving Hormones,” specifically addresses those related to sex.
  • Rollin, Bernard E. and Rollin, Michael D.H. (2001). Dogmatism and Catechisms—Ethics and Companion Animals, Anthozoos, Vol XIV, 1:4-11. Explores the ethics of what the authors refer to as “gonad harvesting” in dogs and cats.

Historic background information:

  • Kuefler, Matthew. (2001) The Manly Eunuch: Masculinity, Gender Ambiguity, and Christian Ideology in Late Antiquity. Chicago:Chicago Series on Sexuality, History, and Society. 245-282.
  • Milani, Myrna M. (2003) Saving Ryan’s Privates: An overview of the pertinent bond, physiological and behavioral factors that contribute to companion animal gonadectomy. Unpublished. This article was written following a presentation by the same name at the 2003 conference of the International Society of Anthrozoology, “The Social Lives of Animals: Human/Non-human Cognition, Interactions, Relationships” Contact for pdf file.
  • Taylor, Gary. (2000) Castration: An Abbreviated History of Western Manhood. London: Routledge.

Medical Studies and Articles

Studies that specific address breast (mammary) cancer and reproductive status in cats or dogs:

Note: Some of these now may be available on-line.
  • Overley, G, Shofer, FS, Goldschmidt, MH et al. (2005) Association between ovariohysterectomy and feline mammary carcinoma. Journal of Veterinary Internal Medicine 19 (4): 560-563.
  • Schneinder, R. (1970) Comparison of Age, Sex and Incidence Rates in Human and Canine Breast Cancer, Cancer, Vol. 26, pp 419-426.
  • Schneinder, R., Dorn, CR, and Taylor, D (1969). Factors Influencing Canine Mammary Cancer Development and Post-Surgical Survival Rates, Journal of the National Institutes of Cancer, Vol. 45, pp1249-1251.
  • Sonnenscheim, E.G.; Glickman, L.T., McKee, LJ, Goldschmidt, MH (1987). Nutritional risk factors for spontaneous breast cancer in pet dogs. American Journal of Epidemiology. 126:4, 736.
  • Sonnenscheim, E.G.; Glickman, L.T., Goldschmidt, MH, McKee, LJ. (1991). Body conformation, diet, and risk of breast cancer in pet dogs; a case-control study. American Journal of Epidemiology. 133:7, 694-703.
  • Sorenmo, Karin U. et al. (2000) Effect of spaying and timing of spaying on dogs with mammary carcinoma. Journal of Veterinary Internal Medicine Journal of Veterinary Internal Medicine Volume 14, Issue 3, pages 266–270 DOI: 10.1111/j.1939-1676.2000.tb01165.x

Other medical studies and articles:

Note: Some of these now may be available on-line.
  • Aaron A, Eggleton K, Power C, Holt PE. (1996) Urethral sphincter mechanism incompetence in male dogs: a retrospective analysis of 54 cases. Veterinary Record.139:542-6.
  • Bryan, J. N., Keeler, M. R., Henry, C. J., Bryan, M. E., Hahn, A. W. and Caldwell, C. W. (2007), A population study of neutering status as a risk factor for canine prostate cancer. Prostate, 67: 1174–1181. doi: 10.1002/pros.20590.
  • Carter, Rene, and Colitz, Carmen, M.H. (2002) The causes, diagnosis, and treatment of canine keratoconjunctivitis sicca. Veterinary Medicine.September, 2002: 680-694.
  • Chao-Chin Chang, DVM, PhD et al. (2009) Evaluation of hormone receptor expression for use in predicting survival of female dogs with malignantmammary gland tumors. (2009) Journal of the American Veterinary Medical Association. 235, No. 4, Pages 391-396 doi: 10.2460/javma.235.4.391.
  • Chu, Karyn et al. Population characteristics and neuter status of cats living in households in the United States. (2009) Journal of the American Veterinary Medical Association. 234, No. 8, Pages 1023-1030 doi: 10.2460/javma.234.8.1023.
  • Cooley, Dawn M. et al. (2002) Endogenenous gonadal hormone exposure and bone sarcoma risk. Cancer Epidemiology Biomarkers and Prevention, 11, 1434-1440, November 2002.
  • Duerr,Felix M. DMV et al. (2007) Risk factors for excessive tibial plateau angle in large-breed dogs with cranial cruciate ligament disease. Journal of the American Veterinary Medical Association. 231, No. 11, Pages 1688-1691 doi: 10.2460/javma.231.11.1688.
  • AJ German. 2006. The growing problem of obesity in dogs and cats. Journal of Nutrition.136: 1940S-1946S.
  • Gilsanz, V. et al (1988) Effect of sex hormones on bone density in rabbits. AJP-Endocrinology and Metabolism.225:4, E416-E421.
  • Grumbach MM. (2000) Estrogen, bone, growth and sex: a sea change in conventional wisdom. Journal of Pediatric Endocrinology and Metabolism Supplement.13  6:1439-55
  • Hart, BL et al. (2014) Long-Term Health Effects of Neutering Dogs: Comparison of Labrador Retrievers with Golden Retriever PLOS One.
  • Hoenig, M and DC Ferguson. (2002) Effects of neutering on hormonal concentrations and energy requirements in male and female cats. American Journal of Veterinary Research. 63(5): 634-639.
  • Howe LM, Slater MR, Boothe HW, Hobson HP, Holcom JL, Spann AC. (2001) Long-term outcome of gonadectomy performed at an early age or traditional age in dogs. Journal of the American Veterinary Medical Association. 218(2):217-21.
  • Kim, NN et al. (2004) Effects of ovariectomy and steroid hormones on vaginal smooth muscle contractility. International Journal of Impotence Research. 16:1, 43-50.
  • Kustritz, Margaret V. Root. Determining the optimal age for gonadectomy of dogs and cats. Journal of the American Veterinary Medical Association, Vol 231, No.11, 1665-1675.
  • Looney, Andrea L. DVM, DACVA et al. (2008)The Association of Shelter Veterinarians veterinary medical care guidelines for spay-neuter Journal of the American Veterinary Association.  July 1, 2008, Vol. 233, No. 1, Pages 74-86 doi: 10.2460/javma.233.1.74.
  • McNicholas, Walter T. Jr  DVM et al.  (2002) Spontaneous femoral capital physeal fractures in adult cats: 26 cases (1996–2001) Journal of the American Veterinary Medical Association. 221, No. 12, Pages 1731-1736 doi: 10.2460/javma.2002.221.1731
  • Meuten DJ. Tumors in Domestic Animals. 4th Edition. (2002) Iowa State Press, Ames, Iowa, p. 575.
  • Neilson JC et al. (1997) Effects of castration on problem behaviors in male dogs with reference to age and duration of behavior. Journal of the American Veterinary Medical Association; 211 (2):180-183.
  • Nolan, R. Scott. (2013) Study shines spotlight on neutering, Assumptions about a mainstay of companion animal practice are called into question. Journal of the American Veterinary Medical Association. 243, No. 9, Pages 1218-1237 doi: 10.2460/javma.243.9.1218
  • Obradovich J, Walshaw R, Goullaud E. (1987) The influence of castration on the development of prostatic carcinoma in the dog. 43 cases (1978-1985). Journal of Veterinary Internal Medicine.Oct-Dec; 1 (4):183-7.
  • Panciera DL. (1994) Hypothyroidism in dogs: 66 cases (1987-1992). Journal of the American Veterinary Medical Association.204:761-767.
  • Passina MA. et al. (2006) Differential effects of Estradiol, Progesterone, and Testosterone on Vaginal  Structural Integrity. 147:1,  61-69.
  • Rawlings, C. Barsanti, J. A., Mahaffey, M.B. (2001). Treating incontinence in spayed female dogs. Journal of the American Veterinary Medical Association.219:770-775.
  • Ru G, Terracini B and LT Glickman. (1998)  Host-related risk factors for canine osteosarcoma. Veterinary Journal (London, England)1998 Jul;156(1):31-9
  • Salmeri KR, et al. (1991) Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development. Journal of the American Veterinary Medical Association.198:1193-1203.
  • Shoemaker Nico J. et al. Correlation between age at neutering and age at onset of hyperadrenocorticism in ferrets. Journal of the American Veterinary Medical Association.Jan 2000, Vol. 216, No. 2, Pages 195-197.
  • Stocklin-Gautschi NM et al. (2001) The relationship of urinary incontinence to early spaying in bitches. Journal of Reproduction and. Fertility. Supplement.57:233-36.
  • Slauterbeck JR et. (2004) Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clinical Orthopaedics and Relatated Research.2004 Dec;(429):301-5.
  • Spain, CV and KA Houpt. (2004). Long-term risks and benefits of pediatric gonadectomy in cats. Journal of the American Veterinary Medical Association. 224(3):372-379.
  • Spain, CV et al. (2004). Long-term risks and benefits of pediatric gonadectomy in dogs. Journal of the American Veterinary Medical Association. 224(3):380-387.
  • Spain CV et al. (2002) When to neuter dogs and cats: a survey of New York state veterinarians’ practices and beliefs. Journal of the American Animal Hospital Association, 38(4): 482-488.
  • Torres de la Riva, Gretel et al. (2013) Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers, PLOS One, DOI: 10.1371/journal.pone.0055937.
  • Ware WA, Hopper DL. (1999) Cardiac tumors in dogs: 1982-1995. Journal of Veterinary Internal Medicine Mar-Apr;13(2):95-103.
  • Witsberger, Tige H. et al. (2003) Prevalence of and risk factors for HD and CCLD in dogs.  Journal of the American Veterinary Medical Association.  232, No. 12. 1818-1824.
  • Zink, M. ChristineDVM, PhD et al. (2014) Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas. (2014) Journal of the American Veterinary Medical Association. 244, No. 3, Pages 309-319 doi: 10.2460/javma.244.3.309.

Behavioral Studies and Articles 

Note: Some of these now may be available on-line.
  • Guy, N.C et al. (2001) Risk factors for dog bites to owners in a general veterinary caseload. Applied Animal Behaviour Science 74:29-42.
  • Guy, N. C. et al. (2001) Demographic and aggressive characteristics of dogs in a general veterinary caseload. Applied Animal Behaviour Science, Volume 74, Issue 1, 11 September 2001.
  • Hart, B.L. (1968) Role of prior experience in the effects of castration on sexual behavior in male dogs, Journal of Comparative Physiological Psychology66:719-725.
  • Hart, Benjamin L.DVM, PhD, DACVB. (2001) Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs. Journal of the American Veterinary Medical Association July 1, 2001, Vol. 219, No. 1, Pages 51-5 doi: 10.2460/javma.2001.219.51
  • Hart BL and RA Eckstein. (1997) The role of gonadal hormones in the occurrence of objectionable behaviours in dogs and cats. Applied Animal Behavioural Science 1997;52:331-344.
  • Kim HH et al. (2006) Effects of ovariohysterectomy on reactivity in German shepherd dogs. Vet J 2006;172(1):154-159.
  • Leuner, Benedetta and Shors, Tracey J. (2006) Learning during motherhood: A resistance to stress. Hormones and Behavior(50) 1, pp 38-51.
  • Lindsey, Steven R. (2000). Handbook of Applied Dog Behavior and Training: Volume I, Adaptation and Learning.Ames, Iowa: Iowa State University Press. Page 186-7.
  • New, John. C. (2000) Characteristics of Shelter-Relinquished Animals and Their Owners Compared with Animals and Their Owners in U.S. Pet-Owning Household. Journal of Applied Animal Welfare Science.3 (3), pp 179-201.
  • Patronek, Gary J., Larry T. Glickman and Michael R. Moyer. (1995). Population Dynamics and Risk of Euthanasia for Shelter Dogs. Vol. VIII, No.1:31-43.
  • Sandstrom, Noah J., Kim, Ju H. and Wasserman, Molly A. (2006) Testosterone modulates performance on a spatial working memory task in male rats. Hormones and Behavior(50) 1, pp 18-26.
  • Wright,John C. PhD and Richard T. Amoss,  (2004) Prevalence of house soiling and aggression in kittens during the first year after adoption from a humane society. Journal  of the American Veterinary Medical Association.   Vol. 224, No. 11, Pages 1790-1795 doi: 10.2460/javma.2004.224.1790
  • Zink, M. ChristineDVM, PhD et al. (2014) Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas. (2014) Journal of the American Veterinary Medical Association. 244, No. 3, Pages 309-319 doi: 10.2460/javma.244.3.309.


Additional Online Sources