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.
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 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.
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 lifespan. 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.
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!
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