The Benefits of Vasectomy & Partial Hysterectomy, and the Myths of Spay/Neuter.

There are better, healthier, and more humane solutions to the pet overpopulation problem. Humane sterilization procedures like vasectomy and partial hysterectomy allow our dogs to live more natural and fulfilling lives. Many of the myths of the benefits of spaying/neutering are pushed only in an effort to increase the number of sterilizations, to assist in curbing pet overpopulation, a worthy cause. Hopefully as better methods of pet sterilization become more and more available, those who have pushed spay/neuter will stop clinging to these myths and join us in promoting humane sterilization of dogs with vasectomy and partial hysterectomy.

Myth: Spaying/neutering is the only way to control pet overpopulation.
  • Vasectomy, partial hysterectomy, and tubal ligation are permanent and effective methods of sterilization, which do not cause any hormonal changes, and therefore will not result in the problems mentioned later in this article. (HumaneFix recommends partial hysterectomy instead of tubal ligation, for the removal of the risk of pyometra)
Myth: Spaying is the only way to prevent pyometra.
  • Partial hysterectomy eliminates the possibility of pyometra to the same extent that spaying does. ("stump pyometra" can still occur in spayed females)
Myth: Spaying neutering reduces cancer risk.
NOTE; These percentages may vary by breed of dog.
  • The risk of hemangiosarcoma is approx 7.4% in spayed females, 1.6% otherwise[1].
  • Mast cell tumors are also more common in spayed females, up to 5.7% in one study[1] Occurring 0 times among unspayed females in the same study.
  • Spaying/neutering was shown to increase the risk of osteosarcoma by 3.8 times in males and 3.1 times in females in one study[2]. Another multi-breed study has shown similar results[2].
  • Spayed/neutered dogs are two times more likely to develop lower urinary tract cancer[2].
  • In contrast, Ovarian tumors occur in approximately 0.05%[2] of females. Testicular tumors occur in approximately 7%[2] of males. Of that small number of testicular tumors, only 6-14% are metastatic.[2]
Myth: Spaying/neutering provides other health benefits.
    NOTE; These percentages may vary by breed of dog.
  • Spaying/Neutering doubles the risk of hip dysplasia in females[1], and increases the risk of hip dysplasia in males[1].
  • Risk of cranial cruciate ligament tearing is rare in unspayed/unneutered dogs, occurring 0 times in one study[1]. The occurrence for spayed/neutered dogs was 5.1% for males and 7.7% in females in the same study[1]. Other studies have shown similar results[2].
  • Spaying/neutering has been shown to increase the risk of hypothyroidism 3 times[2].
  • Allergic/anaphylactic reactions to vaccines are 30% more likely in spayed females and 27% more likely in neutered males[2].
  • Urinary incontinence was shown in 3 different studies to occur in between 4% and 20% of spayed females[2].
  • Urinary tract infections are increased by up 3-4 times in spayed females[2].
  • Risk of perennial fistula is doubled in spayed/neutered dogs[2]
  • In contrast, intact males have an increased risk of benign prostatic hypertrophy[2].

Myth: Spayed/neutered dogs are less likely to be aggressive, better behaved.

  • Spaying/neutering has been shown to increase aggression and fear anxiety[3].
  • Spaying/neutering has been shown to increase owner-directed, stranger-directed, and dog-directed aggression[4].
  • Spaying/neutering has been shown to increase touch sensitivity and non-social fear[4].
  • Spaying/neutering has been shown to increase the occurrence of coprophagia[4]
  • Spaying/neutering has been shown to increase excessive barking[4].

1. Gretel Torres de la Riva, Benjamin L. Hart, Thomas B. Farver, Anita M. Oberbauer, Locksley L. McV. Messam, Neil Willits, Lynette A. Hart. Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. LINK.
Note; Reference number 2 cites MANY different studies, for any data on this page that cites reference 2, please view the PDF for the reference to the individual study.
2. Laura J. Sanborn, M.S. Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs. May 14, 2007 [PDF, All Statistics are cited/referenced within PDF]
3. Parvene Farhoody
. Behavioral and Physical Effects of Spaying and Neutering Domestic Dogs (Canis familiaris) May, 2010 PDF
4. Deborah L. Duffy, Ph.D., and James A. Serpell, Ph.D. Non-reproductive Effects of Spaying and Neutering on Behavior in Dogs. PDF