Laurie's Blog


18 Jul 2020

What about the Ovary-Sparing Hysterectomy?

Canine uterus and ovary 

After last week’s blog,,  that highlighted the research paper regarding when to spay or neuter dog, I had a question about the ovary sparing hysterectomy (OSH).  While it’s something I’ve heard of, to be honest, I had never looked it up!  So, I did a wee literature review just to see what I could find.  


In my search for literature on the Ovary Sparing Spay (OSS) / Hysterectomy, I found 5 resources that seemed to provide adequate referencing.


It appears that this is a good place to start, as they are a main promotor of the technique.  “The Parsemus Foundation works to create meaningful improvements in human and animal health and welfare by advancing innovative and neglected medical research.”


The discussion on this page cites the PROS to be the health benefits associated with keeping a female dog intact based on a variety of studies.


•Reduced incidence of some cancers

•Reduced incidence of hip dysplasia or cruciate ligament tears

•Reduced incidence or urinary incontinence, urinary calculi

•Reduced incidence of obesity, diabetes, hypothyroidism, behavioural issues, or cognitive dysfunction


This page cites the CONS of the OSS as being:

•The risk of mammary tumours 

•The risk of pyometra

They further go on to say that the health benefits may outweigh these risks and that the technique is not new.  It was developed back in the early 70’s with a paper first published in 1972 by Dr. Wendell Belfield, DVM.




This is an article written in 2013.  It brings forth many of the Pro’s and Con’s as mentioned above.   What I took away from this article were the following:

•“…precise technique is essential. 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, also known as ovary-sparing 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”).”

•The 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.

The latter is important because Dr. Kutzler is the author of the 4th paper I chose to include in this review.



This article was published in 2017.  The author discusses ovariohysterectomy (OVH) and ovariectomy (OVE) as the more common approaches to spaying a female dog.  It discusses tubal ligation and the ovary sparing hysterectomy with the following comment:

•“There are no controlled research studies comparing tubal ligation or hysterectomy to OVE or OVH. While ligation of the fallopian tubes or uterine horns can prevent reproduction, it is highly likely that any risks and benefits associated with the presence of ovaries2 are the same for females having a tubal ligation as for those not spayed at all. A complete hysterectomy, including removal of the cervix, likely eliminates the concern for pyometra, while the other risks and benefits of intact status remain unchanged.”

•“Tubal ligation and hysterectomy are uncommon techniques that can prevent reproduction without neutering. However, these procedures are equivalent to not spaying at all with regard to most health effects and do not accomplish most of the goals of spaying female dogs and cats.”



4.Kutzler MA. Gonad-Sparing Surgical Sterilization in Dogs.  Font. Vet. Sci. 12 June 2020. 


This is the most recent article – 2020!  As mentioned before however, it is authored by the veterinarian who has been funded by The Parsemus Foundation to create the training video on how to do the technique.  It does not devalue the information, but is just something important to disclose, I feel.


In this article technique is described and stressed.  Some important features are as follows:

•“It is extremely important that all of the uterine horn adjacent to the ovary is removed and this area is carefully inspected before the ovary is returned to its abdominal location.”

•“The entire uterus must be removed, which is the reason for removing all (or at least part) of the cervix. It cannot be stressed enough that failure to completely remove the entire uterus will predispose for a pyometra.”


There are aspects to living with a dog that has undergone an OSS that include:

•“Although the post-surgical recovery is also like a traditional ovariohysterectomy, bitches that have undergone an OSH will still experience routine estrous cycles and display an enlarged vulva (with no estrual bleeding because the uterus has been completely removed) and estrous behaviors (which includes a willingness to breed).”


In regards to the increased risk of developing mammary cancer, the author points to a study by Torres de la Riva et al. 2013. “However, it is important to note that in at least one study, none of the 120 ovarian intact females developed mammary cancer but two of the spayed females did.”


Additionally, it was brought forth in this paper (and some of the other papers listed above), that this technique is an accepted alternative surgical sterilization technique by the American Veterinary Medical Association.




This last article was shared with me by the person that asked the question about the literature regarding the OSS in the first place.  It is a position statement on the topic by The American College of Theriogenologists (ACT) and the Society for Theriogenology (SFT).   It contains some additional considerations not mentioned elsewhere.


•“The vaginal wall will not be as strong after complete hysterectomy as it was when the cervix was present because the contiguous vaginal wall and cervix have been replaced by fibrous tissue following surgery. If the bitch is accidentally mated, due to the large amount of prostatic fluid that can be produced, the vaginal wall has the potential to rupture, resulting in a potentially life-threatening peritonitis.” 

•“Bitches that have undergone hysterectomy without bilateral ovariectomy will not have bloody discharge when they are in proestrus/estrus as the blood emanates from the uterus, thus it is difficult for owners to know when they are in heat. The only signs a bitch may show are vulvar edema and receptive behavior. This could be problematic when these bitches are taken to public places (e.g. dog day care or dog parks) or if a bitch is left outside unattended while in heat. This may result in accidental breeding which could lead to vaginal rupture or spread of venereal disease (transmissible venereal tumor, brucellosis, herpesvirus). Owners must be counseled on the importance of preventing accidental breeding in bitches that have undergone this procedure.”

•“Veterinarians must be vigilant when obtaining history as to how the bitch was sterilized because vaginal rupture or venereally transmitted diseases may not otherwise be on a differential list, thus delaying appropriate treatment.”


My take away from these articles is that it is imperative for the discussion with clients to be very open an honest.  An ovary sparing spay may not be right for all dog owners, even if the risks are low and the surgery was performed with textbook precision. Not all dog owners are aware of the continued consequences or hypervigilance required to manage a dog with a ‘less visible’ heat cycle.  All in all, because these things come up in conversations (even in the canine rehab department), you now have more information to answer the questions on this topic coming from our increasingly discerning clientele in regards ‘pregnancy preventions options’ for a female dog.  



Tags: spay , neuter , ovary-sparing , hysterectomy

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