Ovary-Sparing Spay

Promoting choice for optimal animal health

Ovary-sparing spay may be a way to have one’s cake and eat it too: a way to spay female dogs (thus addressing population concerns), without the negative health impacts from hormone loss. Ovary-sparing spay is approved by the AVMA. Find veterinarians in your area offering ovary-sparing spay as an option.  Contact us if you are a vet and would like your name listed. Also, visit the Facebook Ovary Sparing Spay and Vasectomy Group for a list of veterinarians who offer alternatives to traditional spay and neuter and to share your experiences.

For a recent overview on the health implications of traditional spay and neuter, and a review of hormone-preserving contraceptive options, see this article in the Innovative Veterinary Care journal.

Pros and cons of spay and neuter

In 2007 a respected veterinarian published a review of the pros and cons of spaying and neutering at different ages (Determining the optimal age for gonadectomy of dogs and cats, Margaret Root Kustritz.) This generated a lot of discussion, and thought leaders are beginning to accept that spay and neuter have both positive and negative health consequences which vary by age, gender, and breed.

In particular, mounting evidence indicates that the health benefits of keeping the ovaries may outweigh the health risks (the risks being mammary tumors and pyometra, which is infection of the uterus).  For example, one study of exceptionally long-lived Rottweilers linked length of ovarian exposure in their first 8 years to total longevity (Waters DJ et al 2009).  This study has some serious design flaws that make it hard to rely on. However, it fits with data in humans; for example, in the Nurses’ Study, women who kept their ovaries when having hysterectomy lived longer than women who had both the uterus and ovaries taken out (Parker WH et al 2009). A publication from U.C. Davis (de la Riva, Hart et al, 2013) looked at two joint disorders and three cancers– hip dysplasia, cranial cruciate ligament tear, lymphosarcoma, hemangiosarcoma and mast cell tumor– and showed that, for all five diseases analyzed, the disease rates were significantly higher in both males and females that were neutered either early or late compared with intact (non-neutered) dogs.

A more recent study by Zink and colleagues (2014) indicated that gonadectomized  Vizslas had significantly increased odds of developing mast cell cancer, lymphoma, all other cancers, and fear of storms compared with the odds for sexually intact dogs. Brain tumors are 11 times more likely in spayed than intact females (Rzechorzek et al 2019).

A significant contributor to the negative health impacts of removing the gonads in dogs is that the natural feedback mechanisms become unregulated. Normally, the hypothalamus and pituitary gland stimulate the production of lutienizing hormone (LH), which then stimulates the production of steroid hormones from the gonads. Without the ovaries, there is no feedback signal to reduce production and LH continues to be produced. A study by Zwida and Kutzler 2016 reported on the implications of high LH levels in dogs without gonads, including  obesity, urinary incontinence, urinary calculi, diabetes mellitus, hypothyroidism, hip dysplasia, cranial cruciate ligament rupture, aggressive and fearful behavior, cognitive dysfunction syndrome, prostate adenocarcinoma and transitional cell adenocarcinoma. A review article on the health problems associated with spay and neuter – and the connection with LH – was recently published by Kutzler in 2020.

In 2019, the New York Times published an essay by Dr. Alexandra Horowitz, a cognitive scientist who studies dogs, in which she argued that spaying and neutering puppies shouldn’t be standard policy — and isn’t automatically the “responsible” choice either.

As a result, a set of highly-motivated and informed potential adopters is beginning to question or resist the mandatory spays required to adopt from a shelter.  In particular, those thinking of adopting breeds known to have greater risk of certain problems after spay may be in this category (for example, Boxers nearly always get incontinence, and Rottweilers and giant breeds are prone to bone cancers).  But this is a highly distressing development to shelters, which fear going backwards on the progress on euthanasia rates and overpopulation that has been made thanks to widespread spay/neuter.

What is ovary-sparing spay (OSS)?

Parsemus Foundation is proposing that we all think more creatively about individualizing spay.  In appropriate situations, veterinarians should be prepared to conduct a hysterectomy, or removal of the uterus and cervix while leaving the ovaries, sometimes called “partial spay.” The procedure is not new: Belfield published on the need for the technique in 1972. OSS removes the nuisance of bleeding during heats, along with the risk of infection of the uterus (pyometra), as long as ALL of the uterus is removed. In traditional spay, there is no need to remove every bit of the uterus, since it will no longer be under stimulation by the ovaries. But in partial spay, the veterinarian must make a large enough incision to pull the uterus up to the surface, see what he/she is doing, and be able to tie off and cut precisely at the cervix rather than just anywhere on the uterus; otherwise it is still possible to have an infection develop in the remaining uterine stump, “stump pyometra.”

If the whole uterus is removed, very few long-term health issues remain. Ovarian cancer is rare enough that the ovaries should not be removed just to try to prevent it. That makes mammary tumors the remaining concern. Although early studies reported a higher incidence of mammary tumors in intact dogs, a  review article indicated that most of these studies were biased, making conclusions suspect (Beauvais et al., 2012). In one study, mammary tumors were reported in 1.25% of older female dogs, with higher incidence in poodles, English cocker spaniels and dachshunds (Zatloukal et al., 2005). As breast tissue is easily visible, detection of mammary tumors is simpler and prognosis for the tumors that become cancerous is good when they are caught early and removed. Thus, many believe that the potential risk of mammary cancer that may occur in females with normal hormones is far less than the greater risk of other types of cancers (which are usually undetectable) in spayed female dogs.

Adopters of dogs who believe that their dog is likely to live longer or be healthier by keeping its ovaries should remain alert to the possibility of mammary tumors as their dog ages.  Owners and their veterinarians may even schedule a mammary-gland ultrasound as part of their dog’s annual exam once she reaches middle age. Meanwhile, the shelter’s population goals are achieved too, because the dog will not be fertile without a uterus.

Details of OSS

Parsemus Foundation has funded a demonstration of ovary-sparing spay by Dr. Michelle Kutzler, a professor of veterinary medicine at Oregon State University and an acknowledged expert and speaker on dog and cat contraceptive advances and reproduction.(Check out this interview with Dr. Kutzler by Dr. Karen Becker of Healthy Pets). In the video below, she demonstrates ovary-sparing spay in a giant breed, a 6-year-old Mastiff who was finished breeding but whose owner was concerned about increased risk of bone cancer and cruciate ligament rupture from traditional ovariohysterectomy spay. Please note that this video shows a real surgical procedure and may be too graphic for some viewers.

Ovary-Sparing Spay from Parsemus Foundation on Vimeo.

For an informative overview of ovary-sparing spay, view the Powerpoint lecture: Hysterectomy by Dr. Michelle Kutzler.

The concept is by no means new; it was first published in 1972 in a groundbreaking publication that is startling in its frankness about the effects of hormone loss. (“The conventional method of unsexing a female dog is by ovariohysterectomy (surgical removal of the uterine horns, ovaries and the body of the uterus). During the many years I have used this procedure, I have often encountered cases of extreme obesity, cardiac stress and urinary incontinence in the middle-aged spayed female…) We are just adding specifics for how to eliminate the risk of pyometra, plus a video demonstration of the procedure in action, to help this option gain more acceptance in the quest for improved dog health.

Again, the cervix must be ligated precisely– one cannot ligate just anywhere on the uterus as is normally done– to prevent the risk of stump pyometra.  Not realizing this fine point has been what has made veterinarians resistant to the idea (“But you’ll get stump pyometra!”); we thank Dr. Kutzler for pointing out that the solution lies in taking extra care with ligation placement. Her slightly larger incision allows her to visualize the area and take this extra care.

The procedure may take slightly longer than high-volume spay, because the cervix must be cut and tied off precisely and a larger incision must be made to see what one is doing. More suture time is involved due to the slightly longer incision. In practice, it takes about 5 minutes longer because of the extra suture time, according to Dr. Kutzler. She reports that some veterinarians say it is actually quicker than an ovariohysterectomy because the need to double ligate around each ovarian stump is eliminated.

Benefits to shelters and veterinarians

Shelters offering this option will have an answer for potential adoptees who would otherwise be turned off from shelter adoption because of mandatory traditional spay; and veterinarians offering the option are likely to be in great demand as it becomes better known. As an added health measure, in deep-chested breeds highly susceptible to stomach torsion (gastric dilatation volvulus) such as Great Danes, Weimaraners, Saint Bernards, and Setters, it may make sense for veterinarians in private practice and owners with the economic means to consider the pros and cons of stomach-tacking, a procedure which might not justify the risks of elective preventive surgery on its own, at the same time as spay—along with discussing behavioral preventive measures.

Parsemus Foundation maintains a list of veterinarians open to performing hysterectomy/ ovary-sparing spay. Please call or email us (see Contact page) if you are a veterinarian who wishes to be included on this list. If you’re a dog owner/guardian and have an open-minded veterinarian who might like to offer this service, you could pass the information along, as there are large parts of the country that are not covered. And please let us know if you have any experience to share, whether especially positive or negative, with contacting one of these vets!

Additional Resources

Download our flyer for a brief overview of the topic.
Facebook Ovary Sparing Spay and Vasectomy Group
For a more normal life for a pet: Partial spay (hysterectomy)” first publication covering why and how to conduct a partial spay on dogs, Belfield, 1972.
“The Pros of Partial Spay”, ovary-sparing spay summary by Elaine Lissner in the Integrative Veterinary Care Journal.
“Hysterectomy powerpoint lecture” by Dr. Michelle Kutzler.
“A Healthier Respect for Ovaries”, Waters D.J. (the author of the Rottweiler study mentioned above).
“Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers”, Hart et al. 2013.
“Golden Retriever study suggests neutering affects dog health” (UC Davis press release on above study)
“Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas”, Zink et al. 2014.
“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” Zwida and Kutzler, 2016.
“Ovary Sparing Spay in Canines: An Alternative to Traditional Ovariohysterectomy”, Mattravers 2017.
“Aggression toward Familiar People, Strangers, and Conspecifics in Gonadectomized and Intact Dogs” Farhoody et al., 2018.
“Alternatives to traditional spay and neuter – evolving best practices in dog sterilization” Brent and Kutzler, 2018.
“Possible Relationship between Long-Term Adverse Health Effects of Gonad-Removing Surgical Sterilization and Luteinizing Hormone in Dogs” Kutzler, 2020.
“Pukka’s Promise: The Quest for Longer-Lived Dogs”, A thought-provoking book by Ted Karasote with a chapter on spay-neuter and health.

Rescued Dog Loie

Rescued Dog Loie

Above: Loie, a perfect example of the dilemma. Abandoned at the rural shelter with her litter of puppies, she was just starting her second heat when the rescue organization saved her.  Remove her ovaries now? Since she has had two heats, this Lab/Rottweiler mix has already lost a fair part of the mammary cancer prevention of early spay. Furthermore, removing her ovaries could quadruple her risk of bone cancer (spayed Rottweilers have a frighteningly high 1 in 4 risk of osteosarcoma) and raise her risk of hemangiosarcoma (also a death sentence) to 10-20%. That’s not to mention the increased risk of CCL tears (which Labs are famous for and which are expensive and/or disabling), incontinence (to which both Labs and Rottweilers are very prone), and an obsession with food which can lead to weight gain unless the new adoptors are careful. But what if she could have a hysterectomy and keep her ovaries (but still be sterilized– no more abandoned puppies) instead?