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.

Modernizing spay practice for females

Hormone-sparing Male Sterilization


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. 

My Views on Sterilization of Shelter Pets  by Dr. Karen Becker

“The subject of spay/neuter is a huge one, and if I were to attempt to cover every aspect of it, this video would be three hours long. Suffice it to say that until we get our nation's shelter systems revamped, animals will continue to be spayed as juveniles. For now, that's that. We won't change anything with this video. Are we pushing for shelter vets to learn ovary-sparing techniques that allow for sterilization without sex hormone obliteration? Yes. But for now, that isn't happening.

I could have made a dozen different choices in my professional career that would have been satisfying, including being a shelter vet. If I were a shelter vet right now, I would be pushing for sterilization techniques that preserve normal endocrine function. I chose the path of a wellness veterinarian because that resonated the most with my personal goals in life. As I've explained, I've made many mistakes. I've apologized directly to the owners and the dogs that I desexed as puppies before I knew any better.

I am as committed as ever to preventing and treating illness in individual family pets. I'm not, however, advocating the adoption of intact animals to people who may or may not be responsible pet owners. Shelter vets don't have the luxury of building relationships with their adoptive families, so all the animals in their care must be sterilized prior to adoption. I totally agree with this. I don't necessarily agree with the method of sterilization being used.”

Why I Believe Sterilization, Not Desexing, Is the Better Option

“As a proactive veterinarian, I have dedicated my life to keeping animals well. I have learned and continue to learn the best ways to help pets stay healthy and the reasons disease occurs. I am also a holistically oriented vet, which means I view animals as a whole – not just a collection of body parts or symptoms.

I believe there is a purpose for each organ we are born with, and that organ systems are interdependent. I believe removing any organ – certainly including all the organs of reproduction – will have health consequences. It's inevitable. It's simply common sense.

There is a growing body of evidence suggesting that desexing dogs, especially at an early age, can create health and behavior problems. When I use the term "desexing," I'm referring to the traditional spay and neuter surgery where all the sex hormone-secreting tissues are removed. When I use the term "sterilization," I'm referring to animals that can no longer reproduce, but maintain their sex hormone-secreting tissues. “

  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


Behavioural risks in male dogs with minimal lifetime exposure to gonadal hormones may complicate population-control benefits of desexing

Neutering: What’s Behaviour Got To Do With It?

Effects of ovariohysterectomy on reactivity in German Shepherd dogs

Behavioral and Physical Effects of Spaying and Neutering Domestic Dogs  (Canis familiaris)

Aggression toward Familiar People, Strangers, and Conspecifics in Gonadectomized and Intact Dogs

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

Why I've Had a Change of Heart About Neutering Pets

Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers

Endogenous Gonadal Hormone Exposure and Bone Sarcoma Risk (Rottweiler)

Gonadectomy effects on the risk of immune disorders in the dog: a retrospective study

Determining optimal age for gonadectomy in the dog: a critical review of the literature to guide decision making

Health Risks of Spay and Neuter

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