Hormone-Sparing Sterilization Procedures

How is hysterectomy or ovary-sparing spay performed in dogs?

The most common hormone-sparing sterilization procedure for female dogs is a hysterectomy, or removal of the uterus and cervix while leaving the ovaries. It is sometimes called ovary-sparing spay (OSS) or partial spay. The procedure is not new: Belfield published on the need for the technique in 1972. OSS removes the nuisance of bleeding during heats, along with the risk of infection of the uterus (pyometra), as long as ALL of the uterus is removed. If some uterine tissue is left, “stump pyometra” may occur. More details of the technique are included in this publication and see Additional Resources for videos and other training information. (Note: the reason that tubal ligation is not usually offered to dogs is that pyometra can still occur).

The female dog will still have hormones, and may behave differently during the heat cycle. And while she cannot get pregnant, she may be attractive to males during heat — so owners may want to keep her indoors or away from intact males during this time.

What about health concerns of keeping the ovaries? Ovarian cancer is rare enough in dogs that the ovaries should not be removed just to try to prevent it. That makes mammary tumors the remaining concern. Although early studies reported a higher incidence of mammary tumors in intact dogs, a review article indicated that most of these studies were biased, making conclusions suspect (Beauvais et al., 2012). In one study, mammary tumors were reported in 1.25% of older female dogs, with higher incidence in poodles, English cocker spaniels, and dachshunds (Zatloukal et al., 2005). Luckily, mammary tumors are pretty easy to detect when rubbing your dog’s belly, and prognosis for the tumors that become cancerous is good when they are caught early and removed. Thus, many believe the low health risk associated with natural hormones is preferable to the more serious potential health risks of traditional spay. Ovary-sparing spay is approved by the American Veterinary Medical Association.

See “Additional Resources” below for details and training materials on OSS.

How is vasectomy performed in dogs?

Vasectomy in dogs is similar to the procedure for men. Each vas deferens (a tube that carries sperm from the testes and epididymis to the urethra during ejaculation) is cut or clamped so that sperm cannot move through. The procedure is completed under anesthesia but is relatively quick and simple. Technical details can be found here. This method of sterilization is accepted by the American Veterinary Medical Association.

There are few health concerns when completing a hormone-sparing sterilization on a male dog, since the only health conditions prevented by neuter are benign prostatic hyperplasia in older dogs (which is treatable by neuter or noninvasive electromagnetic therapy), and testicular cancer (which is also a disease of old age and is treated by castration, which is usually curative).

The dog will be sterile but will still have hormones and be attracted to females in heat. Thus, owners must be willing to keep their dogs from roaming in search of females.