What is a Spay: Ovariectomy versus Ovariohysterectomy for Female Dogs

This is a short informational handout that I developed for my clients discussing simply and briefly the two most common approaches to spaying female dogs. For those interested in more detail, the relevant references are provided.

What is a Spay?
“Spaying” refers to any surgical procedure which removes the ovaries, the source of hormones that cause female dogs to have estrus cycles (“heats”) and allows them to reproduce. There are actually several different ways to spay a female dog. Removing only the ovaries is called an ovariectomy. This can be done through a surgical incision into the abdomen, which is most common, or through several small holes using a special instrument called a laparoscope. Removing both the ovaries and the uterus is called an ovariohysterectomy, and this procedure also can be performed through open surgery or laparoscopy.

Historically, veterinarians in the United States and Canada have mostly performed ovariohysterectomies, while vets in Europe and other places have more often done ovariectomies. However, ovariectomies are becoming more common in the U.S. and are now being taught as the procedure of choice in some veterinary schools.

Why Spay a Dog?
There are several benefits to spaying female dogs. Spaying prevents them from reproducing, which helps reduce the large number of unwanted puppies that must be adopted or euthanized every year. Spaying also prevents infections of the uterus (pyometra). Research has also suggested that spayed female dogs are less likely to get mammary tumors (breast cancer) than intact females, though not all studies agree. And there is some evidence that spayed females may live longer than intact females.

As with all medical procedures, there are also some risks to spaying. Complications associated with surgery are generally uncommon and mild, but serious complications can occur. Spayed females may also be at increased risk of urinary incontinence (leaking urine) later in life, and some orthopedic problems and types of cancer may be more common in spayed dogs of some breeds, though the information on these risks is quite incomplete.

Which Type of Spay is Better?
There is very little difference in the outcomes of different types of spay surgeries. The benefits are the same whether the ovaries and uterus are removed or only the ovaries. Because ovariectomy involves a smaller surgical incision and is generally quicker to perform than overiohysterectomy, there may be a slightly lower risk of surgical complications and a little less discomfort for the patient with this procedure. Laparoscopic procedures require even smaller incisions, so they might be less uncomfortable than open surgeries, but they take quite a bit longer and require expensive specialized equipment.

Some vets believe it is safer to remove the uterus as well as the ovaries in older females who have gone through several heat cycles or have had one or more litters, though there is little research on this subject.

Bottom Line
Since there are no universally accepted guidelines for when to perform different types of spay surgery, individual veterinarians may make different decisions about the best procedure for any individual pet. A pet’s medical record will reflect which procedure was performed so there is no confusion in the future about whether or not the uterus has been removed.


  1. van GoethemB. Schaefers-Okkens A. Kirpensteijn A. Making a rational choice between ovariectomy and ovariohysterectomy in the dog: a discussion of the benefits of either technique Vet Surg. 2006;35(2):136-43.
  2. Lee, S. S.  Lee SeungYong. Park SeJin. Kim YoungKi. Seok SeongHoon. Hwang JaeMin. Lee HeeChun. Yeon SeongChan. Comparison of ovariectomy and ovariohysterectomy in terms of postoperative pain behavior and surgical stress in dogs. Journal of Veterinary Clinics. 2013;30(3):166-171.
  3. McKenzie, BA. Evaluating the benefits and risks of neutering dogs and cats. CAB Reviews: Persp in Agricul, Vet Sci, Nutr, Nat Res. 2010;5(45).
  4. Okkens AC, Kooistra HS, Nickel RF. Comparison of long-term effects of ovariectomy versus ovariohysterectomy in bitches. J Reprod Fertil Suppl. 1997;51:227-31.
  5. DeTora M, McCarthy RJ. Ovariohysterectomy versus ovariectomy for elective sterilization of female dogs and cats: is removal of the uterus necessary?J Am Vet Med Assoc. 2011;239(11):1409-12.




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12 Responses to What is a Spay: Ovariectomy versus Ovariohysterectomy for Female Dogs

  1. Art says:

    And there is some evidence that spayed females may live longer than intact females.>>

    See a healthy respect for ovaries.
    Art Malernee Dvm

  2. Brenda A. Garza says:

    Interesting article. I have a healthy 7-year-old dachshund. Recently, she got a UTI – what the vet called Pyometra. She took the medication and has had normal blood lab work since then. She has also had two menstrual cycles (heats) since then and I have not seen any indication of infection or illness. I want to get her spayed now, but he vet says she needs a hysterectomy. I still don’t fully understand the difference between having her spayed and having her endure a hysterectomy. Can I still spay her? Or is it too late?

  3. skeptvet says:

    “Spay” is just another word for neutering, which means removing the ovaries in a female. Removing the uterus also is optional but not necessary in most cases where a female is neutered early in life. However, after repeated heat cycles, and especially after a uterine infection, the tissue of the uterus has already been changed by exposure to ovarian hormones, and it is considered possible that infections can recur even after the ovaries are removed. In such older dogs, it is commonly recommended to remove the uterus as well as the ovaries to reduce this risk.

    It’s never too late to spay your dog in terms of preventing unwanted litters and uterine problems. In terms of mammary cancer, neutering probably won’t help prevent that at this age, but there’s no benefit to not neutering her either at this age.

    Good luck!

  4. Ada Hartmann says:

    My 6 month old 47 lb GSD/Heeler mix was spayed Thursday and her vet never talked to me about the options and just went ahead and did the ovary removal only, I am really angry that she had the nerve to take this decision away from us and make it on her own.I had never heard of this second procedure prior to last night when she called and said oh by the way this is the procedure I did because this is what I learned in school? I feel she was negligent not discussing this prior. Not the first time she has done this

  5. skeptvet says:

    It sounds like there is a problem in communication here for sure. I will say, however, that the details of surgical procedures are a tough area for shared decision-making in medicine.

    A surgeon chooses whether to use steel or electrocautery, braided or monofilament suture, an interrupted or continuous suture pattern, a Miller’s pedicale knot or a transfixation ligature, and a hundred other options for every spay procedure. It is not possible or appropriate to consult owners for their opinion on each of these hundreds of choices. Ovariectomy versus ovariohysterectomy are different only in that there is a lot of discussion and opinion out there among owners about these procedures, so more often people have preferences compared with most of the other choices that have to be made for every procedure.

    Since the research shows both ovariectomy (OVE) and ovariohysterectomy (OVH) are equally safe and effective, and there isn’t a strong reason to choose one over the other, most vets don’t see a need to treat them as different options for owners to choose between. OVH was done almost exclusively in the US for decades, even though OVE was more common in Europe, and it was never something clients thought about until the OVE procedure began to be more common here in the last ten years or so.

  6. Puppymom says:

    Removing the ovaries only was described as less invasive in the article above (which is better for healing time and I would assume pain control as well), so I’m not sure why you are upset with your vet.

    Getting your uterus removed in addition to ovaries is a bigger surgery, I don’t see why you wouldn’t be happy with the less invasive procedure.

    I agree with Skeptvet…some things should be left to the surgeon to decide. I personally will be looking into an ovariectomy only for my new female puppy, as I feel less invasive is better.

  7. Jaqie H. says:

    According to the article, if a bitch has had many heat cycles then there is still a chance of infection because of the bacteria that enter the uterus during her heat. The infection is called pyometra. It should have been discussed with the client in case the client wanted the uterus removed to prevent that, and avoid the possibility of surgery later down the line. I can understand why this would make someone angry.

    While a vet has skilled training and knowledge that surpass most pet owners it is important to go through all of the options. If a vet feels like a certain procedure should be done then it is up to them to convince the client, not go ahead and make decisions unless it is a life threatening emergency.

    We are losing this kind of report throughout the medical world, and it is not a good thing. Communication is essential, and the vet doesn’t know everything (though sometimes they like to think that they do) simple communication problems are most responsible when it comes to any sort of malpractice death.

  8. skeptvet says:

    There seems to be some confusion, so I want to be clear about the risk factors for pyometra. It occurs because of changes in the susceptibility of the uterus to infection after repeated cyclic exposure to estrogens. The risk is no greater following ovariectomy alone than following ovariohysterectomy. In fact, even in the latter procedure, not all of the uterus can be removed. A small stump always remains, and if a piece of ovary is left behind, dogs who have had a spay that removed the uterus can still develop an infection, known as a stump pyometra. So in terms of the chances of pyometra, the surgeries are equivalent.

    I agree that communication s critical. The problem is that there are limits to the amount and type of information that can be discussed. I could discuss the risks and benefits of neutering and review the many hundreds of studies on the subject for several hours with each client, but this would not be useful information for them, and it would not be feasible. The subject of informed consent is a complicated one involving an intersection of medicine, science, law, philosophy, ethics, and other disciplines. Clients are responsible for making decisions, and they need information to do so. But doctors cannot simply hand over their responsibility for managing the specific medical needs of the patient to clients who lack the knowledge and skills to practice medicine. How much information and how much control each clients wants or needs depends on many factors. In a case like this in which the science shows the procedures to be equally effective, a strong argument could be made that making the client choose between procedures is pointless and not necessary under the principles of informed consent. What position the courts would take on this, though, is hard to predict.

  9. Amie says:

    I have a Havanese mix female recently turned 2 in January. She is a rescue and has a significant heart murmur! I have been advised that she should not be spayed as going under anesthesia may be harmful! I recently learned about ovariectomy and have not had opportunity to discuss with my veterinarian as of yet. Would an ovariectomy be any safer for her to undergo? I surely do not want to risk it if it could be detrimental to her health!

  10. skeptvet says:

    There is very little difference between ovariectomy and ovariohysterectomy in terms of anesthesia. Ovariectomy may be slightly quicker to perfom, but the difference is minimal and probably not significant. However, a heart murmur by itself is not a reason to avoid surgery, and it is often possible to safely anesthetize dogs with benign murmurs or even true heart disease if there is a reason to do so. I would consider having a board-certified cardiologist evaluate your dogs and make a recommendation regarding anesthetic risk.

  11. Priscilla says:

    Since the uterus also put out hormones, after an Ovariectomy, will the female dog still produce enough hormones to arouse a intact male.

  12. skeptvet says:

    There is no significant hormone production from the uterus after ovariectomy, and the uterus typically regresses to a vestigial state. Ovariectomized females and indistinguishable hormonally from those having an overiohysterectomy.

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