Should You OE Or Should You OHE?

Pyometra in an 8-year-old cat.

Photo courtesy of Dr. Phil Zeltzman.


Spays are one of the most common surgeries performed in veterinary practices. However common it is, this procedure has the strange propensity to generate heated discussions between advocates of the ovariectomy (OE) and proponents of the ovariohysterectomy (OHE).

So let’s try to stay away from the controversy and concentrate on the science.

Why is OE vs. OHE even a debate? It is based on the assumption that diseases of the uterus are prevented by removing it—no uterus, no future disease?

OE Preferred in Europe

This argument doesn’t fly in Europe, where OE has been practiced for decades with reportedly no increased incidence of uterine disorders. The risk of uterine tumor in particular is extremely small (0.003 percent).1 In addition, the uterus atrophies after ovariectomy, which may further reduce the risk of disease.

Elizabeth Arnold Stone, a board-certified surgeon at the Ontario Veterinary College in Canada, writes in the last edition of Slatter’s Textbook of Small Animal Surgery: “There is no definitive advantage for removing the uterus in addition to the ovaries during routine neutering. Ovariectomy is less invasive and takes less time than ovariohysterectomy.”2

This also means that anesthesia is shorter with OE.

The complications are similar, although with OE, there is theoretically less risk of hemorrhage, which is the No. 1 complication with OHE. The risk of ovarian remnant syndrome is similar. The risks of urinary incontinence and weight gain are similar.

What about the current literature? This columnist was eager to review for Veterinary Practice News readers over 30 years worth of literature about the art of spaying. Luckily, a group recently did just that for us.

A team from the University of Utrecht in the Netherlands, led by van Goethem, performed an extensive review of scientific articles published from 1969 to 2004. The conclusion of the Veterinary Surgery article is fairly straight-forward: “There is no benefit and thus no indication for removing the uterus during routine neutering in healthy bitches. Thus we believe that OE should be the procedure of choice for canine gonadectomy.”3

First, Do No Harm

Van Goethem, et al, also write: “The surgeon has to choose the least invasive, fastest and safest procedure.” If we agree with that basic principle—reminiscent of the “First, do no harm” mantra—and as long as there are no medical contraindications, then it is difficult to argue that OHE is a better choice than OE in selected cases.

Proponents of OE maintain that the risk of pyometra is minimal since the pet will no longer have heat cycles. Multiple long-term studies confirm this statement: Stump pyometra did not occur in any patient who had undergone OE.4

One concern of OHE advocates is that an OE patient exposed to progestagens—endogenous (tumors, ovarian remnant) or exogenous (medications for dermatological diseases)—may be at risk for pyometra. These risks are small, and there are safer alternative to progestagens for dermatological diseases.

Not Much Help

So we turned to officials to obtain an objective opinion. That didn’t really help.

  • The American Veterinary Medical Assn. doesn’t have an official policy. 
  • The American Animal Hospital Assn. doesn’t have an official position statement.
  • The Professional Liability Insurance Trust doesn’t dictate how veterinarians should practice.

The role of these organizations is not to tell us which procedure is better. It would seem that using the appropriate suture material, the adequate suture pattern, and optimal sterility and surgical techniques would fall under “standards of care” more than which procedure is better.

And of course, the surgery report should document information such as “single ligature” vs. “double ligature” vs. “transfixion,” and which suture material and pattern were used.

Burden of Proof

Should a legal issue arise, the pet owners would have the burden of proof. It would be their responsibility to find an expert willing to testify that procedure A should have been performed instead of procedure B. Likewise, it would be the pet owner’s responsibility to prove that negligence occurred and that standards of care were not met.

Then again, what are standards of care? Who defines them?

They seem to be a fairly vague and changing notion. They are certainly not “area-based” anymore, i.e. they don’t depend on what your local colleagues do. Rather, they are based on up-to-date procedures as defined by current publications, university professors and board-certified specialists.

In the case of OE vs. OHE, there seems to be ample information to document the risks and benefits of both procedures.

Besides, why couldn’t more than one standard of care exist for a medical procedure as long as it is scientifically and ethically acceptable?

Each practitioner should have the prerogative of deciding which procedure is better for each patient. This is no different than deciding which vaccination protocol makes the most sense, or which procedure is better to stabilize a torn ACL, or which suture pattern is ideal for a cystotomy, or which gastropexy technique is stronger for bloat, or which drug cocktail is safer for anesthesia.

It’s a judgment call.

So what’s a concerned practitioner to do? Here are a few suggestions:

  • Check with your state board to learn the current thought.
  • Tailor your treatment plan to each patient.
  • Communicate with the client. Go over the risks and benefits of each procedure.
  • Obtain a signed consent form from the well-informed client.
  • Document everything you do in your medical record and surgery report.

In the heat of the debate, one small word may have been missed. Van Goethem, et al, conclude: “Canine OE can replace OHE as the procedure of choice for routine neutering of healthy female dogs.” The key word is “healthy.”

If the uterus is healthy in a healthy, nongravid female spayed before her first heat, then performing an ovariectomy should be acceptable. If there is any doubt that the uterus may not be healthy, then an ovariohysterectomy is medically indicated.

Here is a final thought from French author Andre Gide, who surely was thinking of spays when he wrote it: “Believe those who are seeking the truth. Doubt those who find it.”  <HOME>

Related Article: Complications?  What Complications?


Dr. Phil Zeltzman is a small animal board-certified surgeon at Valley Central Veterinary Referral Center in Whitehall, Pa.


1.    E. Arnold Stone, Textbook of Small Animal Surgery. Saunders, 2003, p. 1495.

2.    B. van Goethem, et al, “Making a rational choice between ovariectomy and ovariohysterectomy in the dog: A discussion of the benefits of either technique.” Veterinary Surgery. 2006, Vol. 35, No. 2, pgs. 136-143.

3.    L.A.A. Janssens, “Bilateral flank ovariectomy in the dog-surgical technique and sequelae in 72 animals.” Journal of Small Animal Practice, 1991, Vol. 32, No. 5, pgs. 249-252.

4.    L.M. Howe, “Surgical methods of contraception and sterilization.” Theriogenology, 2006, Vol. 66, No. 3, pgs. 500-509.


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