Spay & Neuter
Early spay and neuter in the USA is a common method to control over population. But research now has many questioning whether early spay and neuter is harmless and the best procedure for population control. Another reason given for early spay and neuter is to avoid potential health problems like mammary tumors, and ovarian or testicular tumors. While early spay and neuter has been shown to reduce risks of mammary tumors there is a growing body of research that reflects an increase risks with other serious health problems some of which are: osteosarcomas, hypothyroidism, orthopedic problems, and age-related Cognitive Dysfunction to list a few. It was not that long ago that “vestigial structures and organs” were thought to be useless or close to useless because medical science lacked a full understanding of them. A similar scientific understanding of the canine body continues to grow with more knowledge of the function of various body parts. Many are now recommending a sterilization procedure that preserves normal endocrine function which is important for growth and development.
Many people hope that spaying or neutering will help to calm their dog, or resolve or prevent behavior problems in the future. This is an unreasonable expectation since most behavior is prone to environmental influences and not due to the result of circulating hormones. The one behavior that spaying and neutering does impact is that of unneutered male dogs who are motivated to escape and roam to get to a female dog in season. Female dogs that are unspayed will attract male dogs from great distances when they are in season. Neutering a male dog will remove the frustration, motivation and attraction to females in season.
Genetics and previous learning gives opportunities for behavior to develop, but the environment gives the dog the opportunities to practice a behavior and determine its intensity. A dog’s behavior is influenced by four things. Genetics, early learning, the current environment, and the humans it lives with. A dog’s behavior is based on what they have been taught/learned/or fear of the unknown, or its predicated on what they have been permitted to do. Understand we don’t “fix” normal. We should not be surprised that a guarding breed has guarding tendencies, or a herding breed has herding tendencies or likes to control space, or terriers like to chase small critters, or that sporting breeds (gun dogs) often pickup things and carry things in their mouth. A dog can have tendencies to bark, guard, chase, and urine mark places. But what a trainer looks to identify is whether a dog’s training has been developed for your dog, its breed type, that will give you control over those instincts. Or whether the training was designed to make sure those instincts are completely out of control. Some training is commission based, and other is omission based.
Those things practiced become habits that are hard to break. A dog inclined to bark does not have to be an incessant barker. A guarding breed should permit people you invite into the home without reacting. A dog that likes to chase should be trained only to chase in your presence when given permission. How does the dog perceive their role within the environment and what are the dog’s expectations of how to behave? Dogs should be responsible to you, not for you. If your dog acts as if it is responsible for you, you will lack control over your dog’s behavior. Spaying and neutering should not be expected to resolve behavior problems. This is a function of training and having the right relationship with your dog.
Early spay and neuter is not believed to be the cause of these issues but it’s reasonable to believe that it contributes to fear aggression. If a dog is fearful my approach would generally be to wait on sterilization until the dog has built a solid foundation of trust with people. Imagine it from the dog’s perspective. You lack confidence, you don’t fully trust people, and you are taken to a place with strangers, people you don’t trust, or infrequent acquaintances and you wake up in a strange place, scared, injured, and in pain. This experience has a way of confirming what you believed all along and can lead to more serious problems.
By Dr. Karen Shaw Becker
The vast majority of veterinarians, conscientious pet parents and dog advocates across the U.S. sincerely believe the best thing we can do for our canine companions is spay or neuter them at an early age.
Conventional wisdom holds that dogs must be desexed to avoid diseases of the reproductive organs, as well as to avoid adding to pet overpopulation. This belief is so firmly entrenched in our American culture that pet owners who don’t spay or neuter are considered irresponsible and deserving of scorn.
In veterinary school, students are taught to promote desexing surgery to every pet parent, and the only procedures they learn are full spays and neuters, which desex (remove animals’ ability to produce sex hormones) as well as sterilize (prevent reproduction).
By the time I opened my own animal hospital after veterinary school, I’d been volunteering at a kill shelter for 10 years as a euthanasia technician, and I was adamant that my clients spay or neuter. I desexed thousands of pets when they were very young, convinced I was carrying out my moral obligation as an ethical veterinarian.
The Decision to Perform Spay/Neuter Is Often Based on Convention, Habit or Misconception of Health Benefits
Unlike when I first started out as a veterinarian, today we can refer to a steadily growing body of scientific research that indicates spay/neuter has a significant downside for dogs.
“ … [A]s we’re now learning,” writes veterinarian Dr. Patty Khuly in an article for Veterinary Practice News, “preventing reproductive disease isn’t necessarily a good enough reason to remove organs; not if those organs offer more benefits than they pose risks.”1
In a report for Clinician’s Brief, Dr. Clara Goh, surgical oncologist at Colorado State University’s Veterinary Teaching Hospital states:
“The decision to perform this procedure [spay or neuter] is often based on convention, habit, or misconception of health benefits rather than on an evidence-based assessment of each patient.”2
After I’d been in practice about five years, I started connecting the dots when many of my spayed and neutered patients began to develop endocrine issues. After some research and soul searching, I realized I was insisting on desexing my patients not based on what was physiologically best for them, but rather what I felt was morally best for their owners.
I went through an extended period of feeling overwhelming guilt and the need to apologize to both my clients and patients. I also began changing my recommendations on spaying and neutering.
Risks and Benefits of Spay/Neuter on Large and Giant Breed Dogs
Over the last several years, a number of small, breed-focused, primarily retrospective studies have been conducted on the effects of spay/neuter in large and giant breed dogs, including the Rottweiler and Golden Retriever. Goh of CSU provides the following information to illustrate what the research has uncovered about the potential benefits and adverse effects of gonadectomy:
Condition Effect of Spay on Female Large/Giant Breeds Effect of Neuter on Male Large/Giant Breeds
Overall longevity Mild increase Mild increase
Obesity Moderate increase Moderate increase
Cranial cruciate ligament disease Moderate increase* Moderate increase*
Hip dysplasia Mild increase* Mild increase*
Mammary tumors Marked decrease*
Uterine, ovarian, vaginal tumors Prevents
Testicular tumors — Prevents
Perianal gland tumors — Market decrease
Prostatic carcinoma ---------- Prevents
Lymphoma Mild increase Mild increase*
Mast cell tumors Mild increase —
Hemangiosarcoma Mild increase* Mild increase
Osteosarcoma Mild increase* Mild increase*
Transitional cell carcinoma Mild increase Mild increase
Urinary sphincter mechanism incompetence Moderate increase* —
Cystitis Mild Increase* —
Benign prostatic hyperplasia — Marked decrease
Perineal hernia Moderate decrease
*Age at time of surgery may be important
To summarize the above information: Spaying or neutering large and giant breed dogs decreases or prevents most reproductive organ disease, as you would expect, since conventional desexing surgery removes some or all of those organs and the hormones they produce.
The diseases for which spayed or neutered dogs are at increased risk are, as you also might expect, some of the most common disorders seen in dogs today. They include obesity, cranial cruciate ligament (CCL) ruptures, hip dysplasia, several types of cancer, urine dribbling (incontinence) and cystitis (bladder inflammation).
The Risk of Obesity Is Increased in Spayed and Neutered Dogs
It’s worth noting that obesity in pets is at epidemic levels. In 2017, 56 percent of dogs were overweight or obese, and Khuly believes spay/neuter has played a significant role in the explosion of fat dogs over the last few decades.
“To be sure, it has a lot to do with how we feed ourselves and our families and the ‘food is love’ culture we reside in,” she writes. “It also has a lot to do with the rise of the pet food industry and the proliferation of diets and treats it so effectively markets. But could there be another component we conveniently tend to overlook? After all, everyone knows for sure that spayed and neutered dogs are heavier.
There’s no doubt about it. The inconvenient truth is that dog sterilization leads to fatter dogs. This we know. No one disputes it. Whatever you think about all these new studies on sterilization and certain diseases, the reality of the situation is this: Intact dogs are much more likely to enjoy healthy weights.”
Khuly addresses some great questions to her veterinary colleagues:
- Is spaying and neutering our dogs actually healthier for them?
- Have we been led astray in our thinking on this issue by our community’s desire to prevent pet overpopulation?
- Are veterinarians actually recommending what’s best for our individual dogs?
- Have we researched this issue well enough given our level of sophistication on so many other veterinary issues?
Khuly believes the health of dogs and the problem of pet overpopulation are two separate issues and should be view as such.
“After all,” she writes, “sterilization is not required to achieve normal population levels. In fact, in Europe, for example, where spaying and neutering isn't common, there is no dog overpopulation problem (and, incidentally, a much reduced incidence of canine obesity compared to U.S. dogs).”
Khuly hopes “… responsible Americans are completely capable of keeping their pets from breeding just like Europeans do.” But she laments that every time she brings up the subject, she gets “… lambasted by loud-voiced zealots who claim [she’s] irresponsibly encouraging pet overpopulation by suggesting there may be alternatives to sterilization.”
“… [U]ntil we … stop talking about overpopulation and sterilization in the same breath,” she concludes, “we’ll have to face the inevitable reality: Our dogs are fat, and they’re destined to get fatter. Perhaps one day we’ll be able to look at this problem more dispassionately, but until then, I expect to continue to see more obesity-related disease in dogs than almost any other medical condition.”
Khuly makes a good point about the connection between obesity in dogs and spay/neuter practices, and in general, I’m really happy to see an article like hers in a publication whose audience is primarily the conventional veterinary community. That said, I think of all the risks associated with spay/neuter, overweight and obesity are entirely preventable when pet parents are committed to keeping their dog at a healthy weight.
Some Things to Think About if You’re Considering Spaying or Neutering Your Dog
As I mentioned earlier, over the years I've changed my view on spaying and neutering dogs, based not just on a mounting body of research, but also on the health and behavior challenges faced by so many of my canine patients after I desexed them. That’s why my current approach is to work with each individual pet owner to make decisions that will provide the most health benefits for the dog.
Whenever possible, I prefer to leave dogs intact. However, this approach requires a highly responsible pet guardian who is fully committed to and capable of preventing the dog from mating (unless the owner is a responsible breeder and that's the goal).
It’s important to note that I'm not advocating the adoption of intact shelter animals to people who may or may not be responsible pet owners. Shelter veterinarians don't have the time or resources to build a relationship with every adoptive family, so the animals in their care must be sterilized prior to adoption to prevent more litters of unwanted pets.
My second choice is to sterilize without desexing. This means performing a procedure that will prevent pregnancy while sparing the testes or ovaries so they can continue to produce hormones essential for the dog's health and well-being.
This typically involves a vasectomy for male dogs, and either a tubal ligation or modified spay (a hysterectomy) for females. The modified spay removes the uterus while preserving the hormone-producing ovaries. It also eliminates the possibility of pyometra because the uterus is removed.
Rarely, older, intact male dogs develop moderate to severe benign prostatic hyperplasia (an enlarged prostate) that may be improved with conventional neutering. Generally speaking, mature intact dogs have had the benefit of a lifetime of sex hormone production, so the endocrine imbalances we see with spayed or neutered puppies don't occur when dogs are desexed in their later years.
Unfortunately, veterinary schools in the U.S. only teach full spays and neuters, so unless your own vet has obtained additional training in sterilization techniques that spare the ovaries or testicles (which is unlikely), you’ll have only one surgical option available to desex your pet.
In that case, my suggestion is to wait until your dog has reached full musculoskeletal maturity, and if you have a female, I’d also wait until she’s completed her first estrus cycle before scheduling the surgery. Thankfully, the Parsemus Foundation maintains a list of veterinarians who perform vasectomies and hysterectomies (ovary-sparing spays) — click here to see if there’s a vet in your area.
Providers of alternatives to traditional spay/neuter
This list is provided as a service to individuals seeking a veterinarian willing to perform procedures beyond surgical spay or neuter. Veterinarians are added at their request, and Parsemus Foundation does not endorse any veterinarian. If you are a vet who would like to be included, please contact us at email@example.com.
BEHAVIORAL CONSIDERATIONS OF SPAY & Neuter
Behavioural risks in male dogs with minimal lifetime exposure to gonadal hormones may complicate population-control benefits of desexing
Health Risks of Spay and Neuter
While gonadectomized dogs experience a zero risk of ovarian or testicular cancer and a lowered risk of benign prostatic hyperplasia and anal gland adenocarcinomas, there is mounting evidence that gonadectomy significantly increases the risks of developing many different serious forms of cancer, including hemangiosarcoma, mast cell cancer, prostatic carcinoma, osteosarcoma, and lymphoma/ lymphosarcoma, along with the development of these cancers at earlier ages (44–55). This increased risk of cancer may be related to the long-term effects of elevated blood levels of luteinizing hormone (LH) (56). LH binds to receptors on many tissues throughout the body; this reaction stimulates a number of cellular processes including cell division and nitric oxide release. In addition, gonadectomized dogs have increased risks of a number of orthopedic diseases, including cranial cruciate-ligament insufficiency, hip dysplasia and patellar luxation (44–46, 57–61), and also of numerous autoimmune diseases (62).
Long-Term Health Effects of Neutering Dogs: Comparison of Labrador Retrievers with Golden Retrievers
Determining optimal age for gonadectomy in the dog: a critical review of the literature to guide decision making
Health Risks of Spay and Neuter
44. Torres de la Riva G, Hart BL, Farver TB, Oberbauer AM, Messam LLM, Willits N, et al. Neutering dogs: effects on joint disorders and cancers in golden retrievers. PLoS One (2013) 8(2):e55937. doi:10.1371/journal.pone.0055937
45. Hart BL, Hart LA, Thigpen AP, Willits NH. Long-term health effects of neutering dogs: comparison of Labrador Retrievers with Golden Retrievers. PLoS One (2014) 9(7):e102241. doi:10.1371/journal.pone.0102241
46. Hart BL, Hart LA, Thigpen AP, Willits NH. Neutering of German Shepherd Dogs: associated joint disorders, cancers and urinary incontinence. Vet Med Sci (2016) 2(3):191–9. doi:10.1002/vms3.34
47. Bryan JN, Keeler MR, Henry CJ, Bryan ME, Hahn AW, Caldwell CW. A population study of neutering status as a risk factor for canine prostate cancer. Prostate (2007) 67:1174–81. doi:10.1002/pros.20590
48. Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters D. Endogenous gonadal hormone exposure and bone sarcoma risk. Cancer Epidemiol Biomarkers Prev (2002) 11:1434–40.
49. Knapp DW, Glickman NW, Denicola DB, Bonney PL, Lin TL, Glickman LT. Naturally-occurring canine transitional cell carcinoma of the urinary bladder: a relevant model of human invasive bladder cancer. Urol Oncol (2000) 5:47–59. doi:10.1016/S1078-1439(99)00006-X
50. Prymak C, McKee LJ, Goldschmidt MH, Glickman LT. Epidemiologic, clinical, pathologic, and prognostic characteristics of splenic hemangiosarcoma and splenic hematoma in dogs: 217 cases (1985). J Am Vet Med Assoc (1988) 193:706–12.
51. Ru G, Terracini B, Glickman LT. Host related risk factors for canine osteosarcoma. Vet J (1998) 156:31–9. doi:10.1016/S1090-0233(98)80059-2
52. Sorenmo KU, Goldschmidt M, Shofer F, Ferrocone J. Immunohistochemical characterization of canine prostatic carcinoma and correlation with castration status and castration time. Vet Comp Oncol (2003) 1:48–56. doi:10.1046/j.1476-5829.2003.00007.x
53. Teske E, Naan EC, van Dijk EM, Van Garderen E, Schalken JA. Canine prostate carcinoma: epidemiological evidence of an increased risk in castrated dogs. Mol Cell Endocrinol (2002) 197:251–5. doi:10.1016/S0303-7207(02)00261-7
54. Ware WA, Hopper DL. Cardiac tumors in dogs: 1982–1995. J Vet Intern Med (1999) 13:95–103. doi:10.1892/0891-6640(1999)013<0095:CTID>2.3.CO;2
55. Zink MC, Farhoody P, Elser SE, Ruffini LD, Gibbons TA, Rieger RH. Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas. J Am Vet Med Assoc (2014) 244:309–19. doi:10.2460/javma.244.3.309
56. Zwida K, Kutzler MA. Non-reproductive long-term health complications of gonad removal in dogs as well as possible causal relationships with post-gonadectomy elevated luteinizing hormone (LH) concentrations. J Etiol Anim Health (2016) 1:1–11.
57. Duerr FM, Duncan CG, Savicky RS, Park RD, Egger EL, Palmer RH. Risk factors for excessive tibial plateau angle in largebreed dogs with cranial cruciate ligament disease. J Am Vet Med Assoc (2007) 231:1688–91. doi:10.2460/javma.231.11.1688
58. Duval JM, Budsberg SC, Flo GL, Sammarco JL. Breed, sex, and body weight as risk factors for rupture of the cranial cruciate ligament in young dogs. J Am Vet Med Assoc (1999) 215:811–4.
59. 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) 429:301–5. doi:10.1097/01.blo.0000146469.08655.e2
60. Whitehair JG, Vasseur PB, Willits NH. Epidemiology of cranial cruciate ligament rupture in dogs. J Am Vet Med Assoc (1993) 203:1016–9.
61. Vidoni B, Sommerfeld-Stur I, Eisenmenger E. Diagnostic and genetic aspects of patellar luxation in small and miniature breed dogs in Austria. Wien Tierärztl Monatsschr (2005) 92(8):170–81.
62. Sundburg CR, Belanger JM, Bannasch DL, Famula TR, Oberbauer AM. Gonadectomy effects on the risk of immune disorders in the dog: a retrospective study. BMC Vet Res (2016) 12:278. doi:10.1186/s12917-016-0911-5
63. Hart BL, Eckstein RA. The role of gonadal hormones in the occurrence of objectionable behaviours in dogs and cats. Appl Anim Behav Sci (1997) 52:331–44. doi:10.1016/S0168-1591(96)01133-1