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When should I spay or neuter my dog?



We support the recommendation from the American Veterinary Medical Association (AVMA) that “due to the varied incidence and severity of disease processes, there is no single recommendation that would be appropriate for all dogs.” This post discusses issues you may want to discuss with your veterinarian prior to deciding on the appropriate age for spay/neuter for your dog.

In very general terms, we recommend spaying and neutering between 6 and 9 months of age for most dogs, extending up to 12 or more months for larger breeds (80 lbs and more), depending on the specific history of your breed and your discussions with your veterinarian.


There have been studies done that show both benefits and risk to spaying and neutering at a young age. Some results have not been fully presented in the media. Most of these studies have been performed in large breeds.


Spay/neuter timing needs to consider the behavioral ramifications of allowing a dog to remain intact. At 6 to 9 months of age, most puppies will have had plenty of time to mature skeletally and to reap benefits from sex hormones. Most families, however well-intentioned, are not prepared to deal with sexually mature dogs. Both males and females can be fertile at six months of age. Many families don’t realize that dogs can even breed through many fences, so the longer you wait past sexual maturity to spay or neuter, the greater the risk of inadvertent breeding. Dogs previously not interested in escaping will suddenly find a way out of your yard when hormones hit hard and furiously.


Many families also are not comfortable dealing with multiple heat cycles in a female.

Females can cycle (“in estrus,” “in heat, “in season”) as early as 6 months. Heat cycles involve needing to keep your dog and home clean as well as protecting your dog from accidental breeding. Dogs in heat should never go outside unsupervised, even in a fenced backyard. They are more likely to try to jump or dig out, and many dogs are resourceful enough to breed through fences. Even if your female doesn’t get out, a resourceful male can often jump or dig in. Males can smell a female in heat from as much as a mile or two away and will be attracted to your female’s location. Males are also prone to marking near a female in heat, so even if your female is secure, you can expect intact males near your home to want to be in the area and mark by urinating on or near your home.


It is not an exaggeration to say that even if you are walking with your dog and she is on leash that a male can breed her. A male can approach and be on your female before you realize what is happening. When dogs breed, they “tie” together, and once a breeding starts, it can be over quickly and the male will “tie” your female, meaning he will be attached to her for as long as 30 minutes or more. Trying to separate them at that point can be painful and damaging to both dogs. Besides, once the tie has started, it’s too late to prevent pregnancy.

Females in estrus need to be thoroughly secured from any potentially intact (unneutered) male dogs for the full 21 days of each heat cycle. Heat cycles typically occur twice a year (every 6 months on average).


Males can start to exhibit hormone-related behaviors at about 6 months of age. Hormone-related behaviors are less likely to occur if an intact female isn’t around. However, since a male can smell a female in heat from a great distance, then nearby females can impact the propensity of a male to spray/mark, escape/roam, hump, etc. Unneutered males should never be allowed to roam freely or be off leash in public.


Please see this link for more details about potential hormone related behaviors.


The recent spay/neuter (S/N) research is the latest thing many people are overreacting to without looking into the details. This can include some veterinarians. There are studies showing both advantages and disadvantages to desexing, either at an early age or at all. In general, we do agree that EARLY S/N should be avoided when possible. However, shelters have been performing early (less than 2-3 months) S/N for decades and we have yet to see the epidemics people seem to be predicting when reading these studies.


The bottom line advice from the American Veterinary Medical Association (AVMA) is “due to the varied incidence and severity of disease processes, there is no single recommendation that would be appropriate for all dogs.”


A balanced review of the scientific literature may be found here.


I’ve looked at the literature and compiled a risk matrix along with comments. Per the AVMA, it’s not appropriate to make a blanket recommendation for all dogs. Based on what we have experienced in over 30 years of working with dogs, we have NOT seen S/N associated problems in the breeds we have been involved in (Poodles, Malinois, Labs, Retrievers, various livestock guardian breeds, and outcrosses).


We HAVE seen problems associated with late or no S/N. I personally have lost two dogs to mammary neoplasia, had another affected by it, and we have seen hormone-influenced cancers in other of our dogs. S/N will help prevent this. Some of the risks can also be mitigated by lifestyle, such as obesity and diabetes. Additionally, most breeds in the S/N studies are LARGE breeds with large bred problems (joint problems, etc.). Those issues are much less likely in small or medium sized dogs. Many conditions mentioned in studies are found mainly in certain breeds and are NOT relevant to all breeds. Lastly, incidence rates for some conditions are lower in all dogs, regardless of breed, and this should be taken into consideration as well. The life-span issues should not be ignored as well: Intact dogs have a mean life expectancy of 7.9 years while desexed dogs have a mean life expectancy of 9.4 years.[1][2]


Also not covered in these studies are the lifestyle problems we see in unaltered dogs. Males hump, escape/roam, spray, and have some other undesirable behaviors when not neutered, and these don’t always go away when they are altered.[3] Females also hump, bleed, escape, are more prone to metritis/pyometria (life-threatening uterine infections), and, of course, are at risk for pregnancy. Most pet families are not equipped to properly manage and care for fertile dogs.


Additionally, most of the studies are problematic. They are retrospective, which means that researchers can’t control or account for important variables such as diet, weight, lifestyle, owner’s economic status, and selection bias. They look at old vet records and draw conclusions from those. For the most part these studies also only show correlation, not causation. Retrospective studies are good for finding areas that need further study, but not for drawing scientifically sound conclusions on which to make recommendations.


Finally, most studies are only in one breed, which cannot be extrapolated to all other breeds.[4]


For most circumstances, we recommend spay/neuter between 6 and 9 months. This allows the dogs to have some of the growth benefits of exposure to sex hormones without the risks, including behavior risks. Also, given the mixed conclusions from studies, we feel this “halfway” approach is the most balanced for many dogs. And, per the AVMA recommendation, we also feel that each dog should be looked at individually within the context of its own risks and the lifestyle and needs of the family.[5]


Conditions associated with spay
Conditions associated with spay. www.thehealthyhappydog.com

Conditions associated with neuter
Conditions associated with neuter. www.thehealthyhappydog.com


[1]Bushby PA. The optimal age for spay/neuter: a critical analysis of spay neuter literature. Presented at the Southwest Veterinary Symposium; San Antonio, TX; 2018

[2]Salmeri KR, Bloomberg MS, Scruggs SL, Shille V. Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development. J Am Vet Med Assoc1991;198(7):1193-1203.

[3]Hopkins SG, Schubert TA, Hart BL. Castration of adult male dogs: effects on roaming, aggression, urine marking, and mounting. J Am Vet Med Assoc. 1976 Jun 15;168(12):1108-10.

[4]Bushby PA. The optimal age for spay/neuter: a critical analysis of spay neuter literature. Presented at the Southwest Veterinary Symposium; San Antonio, TX; 2018

[5]Bushby P. Breaking down the optimal spay-neuter timing debate. dvm360 website: veterinarymedicine.dvm360.com/breaking-down-optimal-spay-neuter-timing-debate. Published March 1, 2017.

[6]Hoskins, J. Testicular cancer remains easily preventable disease. Dvm360 website: http://veterinarynews.dvm360.com/testicular-cancer-remains-easily-preventable-disease. Published March 1, 2004.

[7]Santos, R. et al. Testicular tumors in dogs” frequency and age distribution. Arq. Bras. Med. Vet. Zootec. vol.52 n.1 Belo Horizonte Feb. 2000

[8]Kutzler, M. Benign prostatic hyperplasia in small animals. Merck Veterinary Manual website: https://www.merckvetmanual.com/reproductive-system/prostatic-diseases/benign-prostatic-hyperplasia-in-small-animals.

[9]Bryan J. A population study of neutering status as a risk factor for canine prostate cancer. Prostate 2007;1;67(11):1174-81

[10]Feeney DA, Johnston GR, Klausner JS, Perman V, Leininger JR, Tomlinson MJ, 1987: Canine prostatic disease-compari- son of ultrasonographic appearance with morphologic and microbiologic findings: 30 cases (1981–1985). J Am Vet Med Assoc 190, 1027–1034.

[11]Levy, X., et al. Diagnosis of common prostatic conditions in dogs. Reprod Dom Anim 49 (Suppl. 2), 50–57 (2014)

[12]Bryan J. A population study of neutering status as a risk factor for canine prostate cancer. Prostate 2007;1;67(11):1174-81

[13]Panciera  DL. (1994) Hypothyroidism in dogs: 66 cases (1987–1992). J Am Vet Med Assoc 204 (5): 761–767.

[14]Knapp, D., Canine bladder cancer. Perdue University School of Veterinary Medicine website: https://www.vet.purdue.edu/pcop/files/docs/CanineUrinaryBladderCancer.pdf

[15]De la Riva G. Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. PLoS One 2013; 8(2).

[16]Bone cancer in dogs. AKC Health Foundation website: http://www.akcchf.org/canine-health/your-dogs-health/bone-cancer-in-dogs.html. May 10, 2010

[17]Zink MC, Farhoody P, Elser SE, et al. Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas. J Am Vet Med Assoc 2014;244(3):309-319.

[18]Clifford CA, Mackin AJ, and Henry CJ, (2000). Treatment of Canine Hemangiosarcoma, 2000 and Beyond. J Vet Intern Med, 14:479–485.

[19]Slauterbeck JR, Pankratz K, Xu KT, et al. Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clin Orthop Relat Res 2004;Dec(429):301-305.

[20]Whitehair JG, Vasseur PB, Willits NH. Epidemiology of cranial cruciate ligament rupture in dogs. J Am Vet Med Assoc 1993;203(7):1016-1019.

[21]Torres de la Riva G, Hart BL, Farver TB, et al. Neutering dogs: effects on joint disorders and cancers in golden retrievers. PLoS One 2013;8(2):e55937.

[22]McGreevy PD, Thomson PC, Pride C, Fawcett A, Grassi T, Jones B. Prevalence of obesity in dogs examined by Australian veterinary practices and the risk factors involved. Vet Rec. 2005 May 28; 156(22):695-702.

[23]Nelson RW. Diabetes mellitus. In: Ettinger SJ, Feldman EC, editors. Textbook of Veterinary Internal Medicine, 6th edn. Elsevier, St. Louis, MO; 2005. p. 1563–9

[24]Panciera  DL. (1994) Hypothyroidism in dogs: 66 cases (1987–1992). J Am Vet Med Assoc 204 (5): 761–767.

[25]OFA Statistics by Breed website: https://www.ofa.org/diseases/breed-statistics#detail

[26]Bushby PA. The optimal age for spay/neuter: a critical analysis of spay neuter literature. Presented at the Southwest Veterinary Symposium; San Antonio, TX; 2018

[27]Waters DJ, Kengari SS. Exploring mechanisms of sex differences in longevity: lifetime ovary exposure and exceptional longevity in dogs. Aging Cell. 2009;8(6):752-755.

[28]Mammary tumors. American College of Veterinary Surgeons website: https://www.acvs.org/small-animal/mammary-tumors

[29]Waters DJ, Kengari SS. Exploring mechanisms of sex differences in longevity: lifetime ovary exposure and exceptional longevity in dogs. Aging Cell. 2009;8(6):752-755.

[30]Arlt, S et al. Cys c ovaries and ovarian neoplasia in the female dog – a systematic review. Reprod Dom Anim 2016; 51 (Suppl. 1): 3–11

[31]Egenwall A, Hagman R, Bonnett BN, et al. (2001) Breed risk of pyometra in insured dogs in Sweden. J Vet Int Med  15:530-538

[32]Wheaton LG. (1989) Results and complications of surgical treatment of pyometra: a review of 80 cases. J Am Anim Hosp Assoc  25: 563-568.

[33]Jitpean, S. et al. Breed variations in the incidence of pyometra and mammary tumours in Swedish dogs. Reprod Domest Anim. 2012 Dec;47 Suppl 6:347-50

[34]Panciera  DL. (1994) Hypothyroidism in dogs: 66 cases (1987–1992). J Am Vet Med Assoc 204 (5): 761–767.

[35]Knapp, D., Canine bladder cancer. Perdue University School of Veterinary Medicine website: https://www.vet.purdue.edu/pcop/files/docs/CanineUrinaryBladderCancer.pdf

[36]De la Riva G. Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. PLoS One 2013; 8(2).

[37]Bone cancer in dogs. AKC Health Foundation website: http://www.akcchf.org/canine-health/your-dogs-health/bone-cancer-in-dogs.html. May 10, 2010

[38]Zink MC, Farhoody P, Elser SE, et al. Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas. J Am Vet Med Assoc2014;244(3):309-319.

[39]Clifford CA, Mackin AJ, and Henry CJ, (2000). Treatment of Canine Hemangiosarcoma, 2000 and Beyond. J Vet Intern Med, 14:479–485.

[40]Slauterbeck JR, Pankratz K, Xu KT, et al. (2004) Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clinical Orthopaedics and Related Research 429: 301–305.

[41]Whitehair JG, Vasseur PB, Willits NH. Epidemiology of cranial cruciate ligament rupture in dogs. J Am Vet Med Assoc 1993;203(7):1016-1019.

[42]Torres de la Riva G, Hart BL, Farver TB, et al. Neutering dogs: effects on joint disorders and cancers in golden retrievers. PLoS One 2013;8(2):e55937.

[43]Jeusette I, et al. Effect of ovariectomy and ad libitum feeding on body composition, thyroid status, ghrelin and leptin plasma concentrations in female dogs. J Anim Physiol Anim Nutr (Berl).2006 Feb; 90(1-2):12-8

[44]McGreevy PD, Thomson PC, Pride C, Fawcett A, Grassi T, Jones B. Prevalence of obesity in dogs examined by Australian veterinary practices and the risk factors involved. Vet Rec. 2005 May 28; 156(22):695-702.

[45]DeBleser B, Brodbelt DC,Gregory NG, et al. (2009) The association between acquired urinary sphincter mechanism incompetence in bitches and early spaying: A case-control study. The Vet J 187 (1): 42–47.doi:10.1016/j.tvjl.2009.11.004.

[46]Beauvais W, Cardwell JM, Brodbelt DC. (2012) The effect of neutering on the risk of urinary incontinence in bitches - a systematic review. J Sm Anim Pract  53 (4): 198–204.  doi:10.1111/j.1748-5827.2011.01176.x. PMID 22353203.

[47]Nelson RW. Diabetes mellitus. In: Ettinger SJ, Feldman EC, editors. Textbook of Veterinary Internal Medicine, 6th edn. Elsevier, St. Louis, MO; 2005. p. 1563–9

[48]Panciera  DL. (1994) Hypothyroidism in dogs: 66 cases (1987–1992). J Am Vet Med Assoc 204 (5): 761–767.

[49]OFA Statistics by Breed website: https://www.ofa.org/diseases/breed-statistics#detail

[50]Bushby PA. The optimal age for spay/neuter: a critical analysis of spay neuter literature. Presented at the Southwest Veterinary Symposium; San Antonio, TX; 2018

[51]Waters DJ, Kengari SS. Exploring mechanisms of sex differences in longevity: lifetime ovary exposure and exceptional longevity in dogs. Aging Cell. 2009;8(6):752-755.

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