Spaying Your Pets

If you’re the happy owner of a female dog or cat, you will have probably discussed having your pet ‘spayed’ while at the vets. Spaying means removing part or all of the female reproductive tract. Traditionally, a female dog or cat is spayed via an ‘ovariohysterectomy’ – this is the surgical removal of the ovaries (ovario-) and the uterus (aka the womb, -hysterectomy).

However, recently there has been discussion in the veterinary world about whether we should be spaying via an ‘ovariectomy’ instead, where only the ovaries are removed, leaving the uterus intact. So that owners are informed about current thinking, today we will be comparing traditional ovariohysterectomies with ovariectomies, and discuss which may be the preferred choice for your pet.

Ovariohysterectomy vs Ovariectomy: Biological Considerations

The most important thing to remember is that whichever method of spaying is used on your pet, done correctly, there is no chance of her becoming pregnant, so do not worry about this factor. When considering the diseases that we are trying to prevent via spaying, it is often assumed that the more tissue that is left in, the greater the risk of disease – thus, an ovariectomy may be more risky, as the whole uterus is left in. Is this actually true?

A condition called ‘stump pyometra’, where the remaining uterus becomes infected without the ovaries, is often associated with ovariectomies. However, when looking at studies, it has been found that there is actually a very low risk of a stump pyometra following an ovariectomy – and here at Rushcliffe, we’ve never had one. As long as the ovaries are completely removed, the risk is to all intents and purposes zero. If you read otherwise, remember that the only common ways an ovariectomy-spayed animal can get a stump pyometra is if not all ovarian tissue is removed, there is a lack of hygiene during the surgery, or if a drug called progesterone is given. All of these factors are under the control of our veterinary surgeons and are extremely unlikely to follow an ovariectomy if they are careful.

There has also been no reported increase in mammary cancer rates after ovariectomies, as mammary cancer is also linked to hormones from the removed ovaries. It would also not be foolish to assume that uterine tumours are more common if the uterus is left in – however, uterine tumours are also linked with the ovaries, and as with pyometra, proper removal of the ovaries does not seem to increase the risk of associated cancers whether the uterus is still present or not.

The final condition that is often mentioned when discussing ovariectomies is the increased risk of incontinence. Urinary incontinence is a recognised risk with spaying, due to removal of ovarian hormones that assist controlling bladder function. It has been anecdotally said that ovariectomies increase the risk of incontinence, compared to ovariohysterectomies o however, once again, there appears to be no proven link, and both kinds of spay actually carry an equal risk of causing incontinence.

Ovariohysterectomy vs Ovariectomy: Practical Considerations

It would appear that biologically, there is little difference therefore, between ovariohysterectomy and ovariectomy spaying. So what about practical considerations for you and the veterinary surgeon? All of the

following information has been collected from studies, but individual veterinary surgeons may find their experience different in practice.

In general, ovariectomies are a less invasive procedure, as a smaller incision needs to be made on the patient – this can mean there are less risks of infection, breakdown of sutures, pain and other post-operative complications. Recovery times may also be quicker. When performed by a skilled surgeon, ovariectomies can also be quicker, which means the patient is under anaesthetic for less time – this is safer for your pet, and cheaper for you. It may also potentially be easier to perform, as the incision is made nearer to the ovaries than the one made for ovariohysterectomies.

An ovariectomy may also be safer as it has a smaller risk of blood loss – the blood vessels cut during an ovariectomy are much smaller than those cut during an ovariohysterectomy, so if there is bleeding, less blood loss will occur. Furthermore, there is a reduced risk of accidental damage to the ureters (vessels that connect the kidneys to the bladder), as they are easier to avoid with an ovariectomy. Finally, as there is much less tissue to remove with an ovariectomy, high-tech laparoscopic (keyhole) surgeries are much easier to perform.

Final Thoughts

Overall, it appears that there is no increased risk of leaving in the uterus with an ovariectomy, versus taking it out with an ovariohysterectomy. There is a slight risk of stump pyometra following ovariectomies, which do not occur with ovariohysterectomies where the uterus is completely removed, but this risk is so low as to be negligible. Furthermore, ovariectomy is safer, easier and more practical (and in some countries has been the preferred method for many years).

However, it is important to remember that ovariohysterectomies are the traditional and preferred surgery for many vets, and may have been the only method taught to them – performed correctly, ovariohysterectomies are still a very reasonable procedure, and many vets prefer to perform them than risk performing an ovariectomy with which they are less confident.

Given the option, the current thinking is that it is generally preferable to ask for an ovariectomy – although of course it does depend to some extent on the exact individual nature of the patient. We have performed over 1100 ovariectomies, and overall we believe that in 95% of cases they are less traumatic and reduce the risk to your dog. That’s why an ovariectomy or “keyhole spay” is our preferred procedure in the vast majority of cases.