The Pros & Cons Of Ovary Sparing Spay

Updated November 29, 2020

A service available at our Adelaide clinic is the ovary sparing spay. It’s a safe, effective procedure and we’re happy to do it if requested.

However, it’s important to understand the pros and cons first. I want you to compare OSS to tubal ligation or a late spay.

What Is Ovary Sparing Spay?

Also called Partial Spay, an ovary sparing spay is essentially a hysterectomy where only the uterus and one ovary is removed and the other ovary is left in the dog. Unlike in a regular ovariohysterectomy, it is vital that the entire uterus is removed with no remnant tissue.

Why? Prolonged hormonal stimulation of the uterus in dogs often leads to an infection called pyometra or pyometron. Traditionally, spaying female dogs has been as much about preventing this as it has about pregnancy. Even a small amount of uterus left behind can lead to what is called a ‘stump pyometra’.

Advantages of Partial Spay

  • Normal female hormone levels through life
  • Reduced risk of urinary incontinence
  • Reduced risk of overweight dogs
  • Lowered risk of osteosarcoma, transitional cell carcinoma, haemangiosarcoma
  • Lowered risk of cruciate ligament disease and hip dysplasia in certain breeds
  • In common with regular spays, the uterine infection called pyometra is prevented

Disadvantages of Partial Spay

There are four minor disadvantages that may affect all dogs.

  • Larger surgery wound and surgery time (the entire uterus needs removal)
  • During heats, dogs may not be able to socialise in groups
  • False pregnancy (pseudopregnancy) may occur
  • Lifespan increases seen with desexing/neutering may be lost

Additionally, there are three serious disadvantages that might affect some dogs:

  • Mammary tumours can be expected in many bitches
  • Ovarian granulosa cell tumours are also documented
  • Mating with entire males can in rare cases lead to ‘sperm peritonitis’

Of these, mammary tumours are common but they are easily found by a monthly check of the mammary tissue which your vet can demonstrate. There is usually no danger if lumps are removed when small.

Granulosa cell tumours typically secrete oestrogen. Therefore, they are often found after investigation of a persistent vaginal discharge or attractiveness to male dogs.

Read the evidence about health problems caused by desexing here.

Other Spay Options

Let’s compare other ways to desex or neuter female dogs. All of these should meet the requirements of the Dog & Cat Management Board in South Australia and other compulsory desex neuter schemes.

Tubal Ligation

Tubal ligation means preventing pregnancy by cutting and tying the fallopian tubes, therefore leaving the entire uterus and ovaries intact. Here are my views:

  • There is no published surgical method for tubal ligation
  • It’s not as reliable as surgeries where the organ is removed
  • The only benefit is contraception; dogs remain at risk of all the reproductive diseases
  • It may have a place as a short-term measure if desexing is planned later but otherwise we do not offer the procedure

Ovariectomy or Ovary removal

Removal of the ovaries alone is almost identical in effect to the traditional ovariohysterectomy spay. The advantage is in reduced tissue trauma, wound size and surgical time.

Dogs after ovariectomy will not have seasons, and the risks of pyometra and mammary cancer should remain low, owing to the lack of hormonal stimulation. Just like traditional spays, ovariectomy can (and should) be performed early or late depending on the patient’s best interests.

Late Desexing/Neutering

A valid third alternative is to still remove the ovaries, but wait until the dog is at or near full skeletal maturity. By doing this you should retain most of the benefits of oestrogen without much risk of harm.

  • The studies on risks of cruciate ligament problems or hip dysplasia compared two ages of desexing, not desexed versus entire. Dogs desexed over one year of age had much lower rates. Currently, this applies only to Labradors, Golden Retrievers and German Shepherds but other large breeds may also be affected.
  • Your dog still achieves full female development, including reduced adult female size (yes, oestrogen causes earlier growth plate closure).
  • You should retain all the benefits of early desexing including increased lifespan, reduced mammary cancer, zero pyometra, no heats.
  • The risk of incontinence is only 3% and is usually easily treated
  • Other effects of loss of female hormones are unproven or speculative
  • Late desexing means over one year of age.

If there is one take-home message it is this: despite the risks of some diseases being higher in desexed dogs, population level evidence supports desexed dogs having a longer lifespanIn large studies, the lifespan of neutered or spayed female dogs is 0.8 to 1 year greater than entire females. It is unproven and unlikely that this benefit will persist by just removing the uterus.

Related: A Comparison Of Male & Female Dog Desexing & Contraception

Thrusfield, M. V., Holt, P. E., & Muirhead, R. H. (1998). Acquired urinary incontinence in bitches: its incidence and relationship to neutering practices. Journal of small animal practice, 39(12), 559-566.

By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story!
Have something to add? Comments are welcome below and will appear within 24 hours.


26 Replies to “The Pros & Cons Of Ovary Sparing Spay”

  1. Hello Andrew, I breed Griffons, dogs under 5kg. I desexed my first litter at 12 weeks and there have been no issues at all. The subsequent litters were not desexed after a lot of pressure from the other breeders, but I feel like the benefits of desexing my puppies will far outweigh the possible negatives. For larger breeds I certainly understand why you would delay desexing but Im not sure about the smaller breeds.

    1. Hi Michele. It’s fair to say that the problems we see with early spay are likely to be greater for the larger breeds of dogs, but they won’t disappear completely for small and toy breeds either. Therefore, the decision to spay before six months of age in any dog will come with some inherent disadvantage, even if it is small. It’s up to each breeder to make an argument that there is enough advantage with earlier desexing to offset this (I can only think of prevention of backyard breeding).

  2. Hello Andrew! Our two year old German Shepherd recently had a partial spay. She began spotting fairly heavily nine days ago and we are concerned. We knew that there was a chance of some spotting with a partial spay but this doesn’t seem right. What is your advice? Thank you!

    1. Hi Cathryn. Some spotting is normal during seasons but it’s best you get your vet to have a look given that the surgery was done so recently.

  3. Hi Andrew, We have a female standard poodle who is now 7 months old and we have delayed her desexing (removing both ovaries and uterus) until her growth plates are closed and skeletal development complete. We planned to review after her first season, and even consider waiting for her second season to be sure of avoiding joint issues in later life. We have a very caring and competent vet who is not in agreement with us on this issue, and mentioned that the risk of mammary tumors is increased if we wait until she had two seasons. We have researched as much as we can, including reading your excellent papers on the issue but are still confused. We really want to give her the best possible life free of preventable disease. We are both home with her all day and our home is well fenced, so management during her seasons is not an issue. Of course we would never repeat your advice to our vet, but are genuinely interested in your opinion of our particular situation. Thank you.

    1. Hi Malcolm. Your vet is right in that the risk of mammary cancer is likely to increase with each season. However, most vets would agree that even after two seasons the risk is still quite low. However, I would follow the advice in our page on the best age to desex a dog and do it at around one year of age. That’s probably the sweet spot in balancing risks and benefits.

  4. My nearly two year old first generation labradoodle had a one ovary sparing spay as a puppy by the breeder with removal of one ovary and uterus Our vet keeps wanting to remove her ovary that is left which I think will be a difficult operation as it will be floating around and harder to find and I’m not happy to put my dog through another surgery when the benefits and risks are similar. What are your thoughts on this. She does come into heat twice a year but so far no other problems.

    1. Hi Pam. It’s totally up to you, but I would probably go ahead and remove the second ovary. It’s true that the wound will probably need to be larger in order to find it, but that should be the only disadvantage. If you leave it, then the information on this page gives you a guide on what to expect (mainly ongoing seasons and later mammary tumours).

  5. Hi Andrew,

    Firstly a big thank you for your articles, I really appreciate the evidence based conclusions even if it happens to go against the norm.

    I’ve read your articles on desexing particularly delayed desexing. As a result of stumbling across it I did further research and had my vet write an exemption letter to the council for delaying the compulsory 6month desexing in our area (QLD)for
    our male English Mastiff ( until
    18 months – should I try to extend to 2 years?)

    After bringing this to their attention and the vet doing his own research they thanked me and are now recommending this to all of their giant breed clients.

    Now we are picking up a 5mo female British Bulldog pup as a companion this weekend. Although we are aware of the array of health issues (I still question this decision ethically) my husband has wanted one since he was a kid.

    We have done our research on her lines and have undertaken a health check with the most experienced vet we could find in the area, asking specifically to check on conditions bulldogs are prone to on top of the standard checks.

    Anyhow, given that they are prone to displaysia and ACL’s (and pretty much everything!) what age would you recommend getting her desexed?

    Many thanks again Andrew!

    1. Hi Carly. Thanks for the feedback. Re your mastiff, 18 months should be quite sufficient but I’ll also repeat that behaviour comes first. If you notice any aggression (unlikely in the English), that takes priority. As for a British Bulldog, their joint issues seem unrelated to desexing (they have unusual stifle joints) so desexing time isn’t likely to matter much. I’d go with 6-9 months.

  6. “In large studies, the lifespan of neutered or spayed female dogs is 0.8 to 1 year greater than entire females. It is unproven and unlikely that this benefit will persist by just removing the uterus.”

    You should learn to properly cite your sources good Dr. The ‘research’ that supports complete desexing in dogs and cats is replete with misinformation, scare tactics and twisted ‘partial’ facts (carefully phrased for effect) in the USA, where veterinary medicine is still in the ‘dark’ ages. Come to Europe and we can show you many OLD dogs who are intact. These same dogs also did not have aggression issues, mammary or testicular tumors, skin allergies, cancers of the spleen, … and a host of other issues ALL related to your sick desire to remove the sex organs of an animal. Those are the FACTS.

    1. Trust me- no one would be happier not to be speying dogs, but these are the facts as they stand. I would be delighted to be shown evidence to the contrary but the studies so far are clear. One such peer-reviewed scientific paper is:
      Michell, A. R. Longevity of British breeds of dog and its relationships with sex, size, cardiovascular variables and disease. The Veterinary Record 145.22 (1999): 625-629.
      Others can be found in my page on desexing male dogs.

  7. DearAndrew
    I am SO glad you mentioned late desexing. I totally agree.I have just done medical science and my mother had a friend that was hysterectomised at 20. At 80 her spine crumbled so that her ribs touched her hips. I was always suspicious of removing vital hormones too early. Otherwise why would evolution have them at all?

  8. Hello Sir..My dog is 9 years old..Last year her uterus was removed but not her overies..She is now having Pseudopregnancy..Is there any sort of danger???

    1. Hi. Pseudopregnancy is not normally a health risk to a dog but it can be very distressing for them, and sometimes also quite prolonged. In some countries there is a product called Galastop that can help, but the condition should pass with time. This is certainly one of the disadvantages of ovary sparing spay

  9. What do you think about just taking ovaries, and leaving uterus ? Less avasive surgery, and does away with heat cycle.. been told no risk of pyametry without ovaries? What do you think?

    1. Good question Sue. I think that ovariectomy alone is a good option. I have only done it rarely but you are right that pyometra is a minimal risk without ovarian stimulation. The reason we rarely leave the uterus is simply that it is quite easy to remove, and prior to the first heat, it’s not very traumatic surgery. Lararoscopic spey could be an example of when ovariectomy alone would make sense.

  10. My 8 month cherry spayed before 4 month but before 4 days she came in heat and mating too..i was so angry on dr and called him ,he says during surgery one ovary was left due to some complications and now we wont able to remove the left ovary because it get deep inside.
    So my cherry will come in heat but no puppies,actually i dont want her to come in heat.please advise

    1. Hi Smita. Why don’t you ask a second vet if they can go back to remove the ovary? It should be quite possible to do this and a second opinion won’t hurt. Otherwise, yes, your dog will continue to have heats. If that’s the case it’s essential that the vets removed the entire uterus down to the cervix.

    1. Thanks Mary. TCC is not a common cancer but I’m also not aware of studies that report an increased incidence. If you know of any, please post the info & I will look it look into it for you.

  11. Thanks for your response Andrew. I must say, no one seems to offer this procedure in Sydney and nobody seems to have heard of it being done in pets. They do offer the partial desex with scope where only the ovaries are removed. I am very surprised at how rare. Well done for offering your unique skills to your local community. Their good fortune indeed.

  12. Good morning

    Thank you for your article on desexing options. I am in Sydney north. Do you have an colleagues who perform tubal litigation on dogs in my city?

    Many thanks

    1. Hi Tania- I’m not aware of which vets offer the procedure but it’s not difficult for any experienced vet to perform. You should be able to find someone by ringing around.

      1. Hi Andrew!
        Thank you for educating owners on spay and neuter options available in the US. I have two female Westies (10 month old & 3.5 month old) and am considering either OSS or the surgery that only removes the ovariectomy. Is the percentage of urinary incontinence lower with an ovariectomy as well? My vet mentioned that about 10-20% of the hormones remain with the cervix still in place. I would like to give my girls a long life without any health issues and am trying to decide which procedure is beat. Thank you!

      2. Hi Ania. It’s likely that ovariectomy will have similar rates of urinary incontinence to a full spay procedure. However, it hasn’t been studied specifically to my knowledge and I suspect that your vet may be correct in saying there will be a slight reduction in risk.

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