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Does spaying and neutering reduce aggression?


Does spaying and neutering reduce aggression in canines where a claim can be made that it will protect the public? A significant number of canines that have
been sterilized are responsible for killing people and data shows high numbers of sterilized canines show up on dog bite incident reports.

ACF(American Canine Foundation) is preparing response briefs in our federal lawsuit, Defense attorneys in their briefs are making claims that spay and neuter will protect the public by stopping canine aggression. ACF is moving forward in our federal lawsuit against LA County, San Francisco and California State Agencies.


Below is a text taken from data using scientific proof from an FDA Federal Study addressing testosterone in canines:

Addressing The Testosterone Issue

"Testosterone plays a role in modulating certain behaviors such as roaming, urine marking in-doors, sexual mounting and aggression toward other dogs
(versus playful activity or dominance). Neutersol reduces the male hormone, testosterone, by 41-52% while surgical castration reduces testosterone by 95%. These behaviors may persist after either neutering method.

While testosterone plays a role in affecting certain sexually dimorphic behaviors, it is not the only factor. In fact, the veterinary behavioral textbooks point out that there are multiple contributing factors with regard
to these behaviors. Surgical castration does not completely eliminate these behaviors. The controlled scientific studies that have assessed the effects
of surgical castration with regard to behavior have shown that most dogs continue exhibiting these behaviors. Aggression toward humans shows little significant effect after surgical castration. Surgery can have an effect in
some of these, but is far from absolute. The FDA has reviewed the data for both surgery and Neutersol and included wording in the prescribing information of Neutersol addressing this fact, "As with surgical castration, secondary male characteristics (roaming, marking, aggression and mounting) may persist."



Here are some research publications that conclude that early spay/neuter correlates with a high incidence of ACL damage and cancer.


Texas Tech University has PhD's that have published a study on ACL and spay/neuter correlation. This type of injury is one of the most painful to dogs....and of course cancer is deadly..




1. Salmeri KR, Bloomberg MS, Scruggs SL, Shille V.. Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development. JAVMA






3. Grumbach MM. Estrogen, bone, growth and sex: a sea change in conventional wisdom. J Pediatr Endocrinol Metab. 2000;13 Suppl 6:1439-55.



4. Gilsanz V, Roe TF, Gibbens DT, Schulz EE, Carlson ME, Gonzalez O, Boechat MI. Effect of sex steroids on peak bone density of growing rabbits. Am J

Physiol. 1988 Oct;255(4 Pt 1):E416-21.



5. Slauterbeck JR, Pankratz K, Xu KT, Bozeman SC, Hardy DM. Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clin Orthop Relat Res. 2004 Dec;(429):301-5.


6. Spain CV, Scarlett JM, Houpt KA. Long-term risks and benefits of early-age gonadectomy in dogs. JAVMA 2004;224:380-387.



7. Ware WA, Hopper DL. Cardiac tumors in dogs: 1982-1995. J Vet Intern Med1999 Mar-Apr;13(2):95-103



8. Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters D, Cancer Epidemiol Biomarkers Prev. 2002 Nov;11(11):1434-40



9. Ru G, Terracini B, Glickman LT. Host related risk factors for canine osteosarcoma. Vet J. 1998 Jul;156(1):31-9.



10. Obradovich J, Walshaw R, Goullaud E. The influence of castration on the development of prostatic carcinoma in the dog. 43 cases (1978-1985). J Vet Intern Med 1987 Oct-Dec;1(4):183-7







12. Meuten DJ. Tumors in Domestic Animals. 4th Edn. Iowa State Press, Blackwell Publishing Company, Ames, Iowa, p. 575



13. Stocklin-Gautschi NM, Hassig M, Reichler IM, Hubler M, Arnold S. The relationship of urinary incontinence to early spaying in bitches. J. Reprod.


Fertil. Suppl. 57:233-6, 2001



14. Pessina MA, Hoyt RF Jr, Goldstein I, Traish AM. Differential effects of estradiol, progesterone, and testosterone on vaginal structural integrity. Endocrinology. 2006 Jan;147(1):61-9.


15. Kim NN, Min K, Pessina MA, Munarriz R, Goldstein I, Traish AM. Effects of ovariectomy and steroid hormones on vaginal smooth muscle contractility. Int J Impot Res. 2004 Feb;16(1):43-50.



16. Aaron A, Eggleton K, Power C, Holt PE. Urethral sphincter mechanism incompetence in male dogs: a retrospective analysis of 54 cases. Vet Rec. 139:542-6, 1996



17. Panciera DL. Hypothyroidism in dogs: 66 cases (1987-1992). J. Am. Vet. Med. Assoc., 204:761-7 1994



18. Howe LM, Slater MR, Boothe HW, Hobson HP, Holcom JL, Spann AC. Long-term outcome of gonadectomy performed at an early age or traditional age in dogs.


J Am Vet Med Assoc. 2001 Jan 15;218(2):217-21.