The Spay and Neuter Controversy

There is currently a great controversy in the Animal Care Field regarding the “right” age to spay or neuter a pet and the “right” technique to use. As there is no right answer right now, here are links to important research that can help you decide what is right for your pet. We also have more information on our Spay or Ovary Sparing Spay page as well as our Neuter or Vasectomy page.

Is a vasectomy or ovary-sparing spay right for my dog?

Your decision to spay or neuter your pet must be made on a case-by-case basis. This decision should be made between you and your veterinarian, taking into consideration your pet's age, breed, sex, health status, intended use, household environment, and temperament. While there are health benefits to spaying and neutering, the benefits must be weighed against the health benefits of retaining the sex hormones achieved by leaving your pet intact (not neutered or spayed). These advantages and disadvantages pertain not only to the canine athlete or performance dog but to all dogs regardless of lifestyle. Each patient must be considered individually – we do not have a one-size-fits-all answer for whether it is best to remove or not remove the gonads (testes or ovaries) for your pet.

If you have determined you do not plan to breed your dog, male or female, you are now faced with other decisions.

What is a vasectomy? What is an ovary-sparing spay?

A vasectomy is a surgical procedure where a portion of the vas deferens, the tube that carries sperm from the testicle where they are formed to the outside to fertilize the female, is removed. By doing this, even if the male dog mates with a female, the mating will not be a fertile one. The testicles remain in the scrotum and continue to produce testosterone. The male will still be interested in and can mate with females, may still lift his leg to mark territory, is still prone to benign prostatic hypertrophy, and could develop a testicular tumor, perianal tumor, or perineal hernia.

An ovary-sparing spay is when one or both ovaries are left in the abdomen, near the kidneys, but the uterus and cervix are removed. Because the uterus is removed, the female will not be able to become pregnant, even if a mating occurs. The female will still have heat cycles and be attractive to male dogs. She will have little to no bloody vaginal discharge during her heat cycles.

If you chose surgery, at what age should you “alter” your pet?

If you opt for a non-traditional approach, the vasectomy or ovary-sparing spay, when you leave the testes or ovaries but interrupt the reproductive tract to prevent fertility, you may consider doing this at any age. Because the male or female sex organs are left to function, your dog will still have his or her hormones. Research has shown that there can be positive effects of the sex steroid hormones. The sex steroids are hormones produced by the ovaries and testes and are only present in intact males and females. For canine athletes, Dr. Christine Zink recommends waiting until after 14 months of age (the age at which the growth plates have closed) for males and females to be neutered or spayed.

Should you opt for a traditional neuter or spay? At what age?

If you opt for a traditional neuter or spay, the age at which this is done is important. Removing the testes or ovaries interrupts the hormonal axis of the sex hormones with the pituitary and other organs. There are age-related conditions to consider when making this decision. Since gonadectomy prior to puberty or sexual maturity may make the risks of some diseases higher in certain breeds or individuals, the option to leave your pet intact should be available to you. If you opt to leave the gonads, the testes, or ovaries, this can be done at any age, as young as 8 weeks of age. If you opt to remove the gonads, testes, or ovaries, the age should be decided in a conversation with you and your veterinarian. Many times, we recommend waiting until at least 6 months of age or older, usually past puberty, due to health and behavioral advantages.

What are the advantages of retaining the testes or ovaries?

Health advantages include:

Lower incidence of hemangiosarcoma (cancer usually found in the spleen or heart) in males and females.
Lower incidence of osteosarcoma (bone cancer) in intact males and females.
Lower risk of transitional cell carcinoma (bladder cancer) in intact males and females.
Lower risk of prostatic adenocarcinoma (prostate cancer) in intact male dogs compared to neutered male dogs.
Lower incidence of obesity in intact male and female dogs, which may be due at least partly to increased metabolic rate.
Lower incidence of urinary incontinence in intact females
(equivocal if females are spayed after 5 months but before their first heat).
Lower incidence of urinary tract infection in intact females.
Lower incidence of autoimmune thyroiditis and hypothyroidism in intact males and females.
A reduced incidence of cranial cruciate rupture in intact males and females.
A reduced incidence of hip dysplasia in male and female dogs that are not neutered or spayed before 5 months of age.
Anesthesia and surgery are not appropriate for some patients with high-risk medical conditions.
Lower incidence of adverse reactions to vaccines in intact
males and females.
Evidence of increased lifespan in females left intact past puberty. David J. Waters, associate director of Purdue University's Center on Aging and the Life Course and a professor in the Department of Clinical Sciences. "Taking away ovaries during the first 4 years of life completely erased the female survival advantage. We found that female Rottweilers that kept their ovaries for at least 6 years were 4 times more likely to reach exceptional longevity compared to females who had the shortest lifetime ovary exposure."

Behavioral advantages include:

Less aggression towards people and animals in intact females.
A decreased incidence of cognitive dysfunction in intact males and females.
Less fearfulness, noise phobias, and undesirable sexual behaviors in intact males and females.

What are the disadvantages of retaining the testes or ovaries?

Health disadvantages include:

Increased risk of mammary (breast) cancer in intact females. This increased risk of mammary (breast) cancer occurs with each subsequent cycle, and the benefit of spaying does not disappear until the animal reaches old age. Mammary cancer is one of the most common types of cancer in small animals. Mammary neoplasia is malignant under 50% of the time in dogs, but few dogs die from breast cancer due to low metastatic rates and early detection and treatment.
Increased risk of ovarian cancer in intact females. The incidence and mortality risk for ovarian cancer are very low.
Increased risk of testicular cancer in intact males. The incidence for testicular cancer is common, but malignancy and mortality are very low.
An increased risk of pyometra in intact female dogs, and this risk increases with increasing age. Varies by breed – review this with your veterinarian.
Risk of unwanted pregnancies if an OSS or vasectomy is not performed.
An increased risk of prostatitis, benign prostatic hyperplasia, prostatic cysts, and squamous metaplasia of the prostate in intact male dogs.
An increased incidence of perineal and inguinal hernia and perineal adenoma in intact male dogs.

Behavioral disadvantages include:

Inter-dog aggression may be due to competition for available territory or availability of cycling animals.
Increased risk of wandering and being hit by a car in intact dogs.
Increased incidence of urinary marking in intact males.
Ongoing sexual behaviors, including heat cycles in females who have had an ovary-sparing spay.

What We Can Learn From Old Dogs

The fascinating TedX presentation by Dr. David Waters on the last night of his Old Gray Muzzle Tour. Sit down with a big bowl of popcorn and your favorite drink to watch this one – you will be fascinated by his breaking information – The Oldest Dogs as Our Greatest Teachers. ~via YouTube

Dr. David Water’s Old Gray Muzzle Tour

The tour that investigated the link of lifetime ovary exposure (age of spaying/not spaying) with longevity in the dog. ~via Purdue Research Park

Exploring mechanisms of sex differences in longevity

Lifetime ovary exposure and exceptional longevity in dogs. ~via Wiley Online Library

More information about Dr. David Water’s research

via Gerald P. Murphy Cancer Foundation

Long-Term Health Risks and Benefits Associated with Spay/Neuter in Dogs

A comprehensive article on the benefits and risks of spaying and neutering. ~via National Animal Interest Alliance – NAIA

Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers

via PLOS

More information on several spay and neuter topics

via Society for Theriogenology

Early Spay-Neuter Considerations for the Canine Athlete

Dr. Christine Zink’s article looks at how spaying and neutering affect the athlete. ~via Canine Sports

Is Early Neutering Hurting Pets?

by Dr. Alice Villalobos ~via Veterinary Practice News

Reproductive Biology and Medicine of Domestic and Exotic Carnivores

Dr. Iris Reichler's research on spaying and neutering – the European perspective. ~via International Veterinary Information Service – IVIS

Aggression Toward Familiar People, Strangers, and Conspecifics in Gonadectomized and Intact Dogs

An interesting study on if when a male dog gets neutered plays a role in aggression. ~via Frontiers in Veterinary Science

The Adverse Health Effects of Early Spay and Neuter in Golden Retrievers

One Golden Retriever Breeder's perspective on spaying and neutering. ~via Sunbeam Goldens

Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence

via NIH National Library of Medicine

The Ovary Sparing Spay (OSS)

The heat cycles remain and there is no protective effect for preventing breast cancer, but as you can read below, there may be longevity benefits to leaving the ovaries and removing the entire uterus including the cervix. This requires a longer incision but may be a better option.