To spay, or not to spay? That is the question.

Whether ’tis nobler in the mind to suffer The slings and arrows of animal rights activists Or to take arms against a sea of troubles…
(With apologies to The Bard)

(Originally posted May 13, 2020 – Updated July 15, 2022)

Many people would have you believe the spay/neuter decision is easy. “Yes!” and “Right away!” they’ll say. “We have to prevent pet overpopulation and animal suffering!”

But it’s not that straight forward. Not every intact animal contributes to overpopulation. Nor is spaying and neutering without pain and suffering.

RESCUE ORGANIZATIONS

As a country, I think we’ve made great strides in controlling pet overpopulation. Are there still animals in need? Certainly. Is spay/neuter the answer in every case? No.

I believe our rescue organizations are desperately needed and deserve thanks from every pet owner. However there are still animals who wind up in shelters and never leave. I’ve been there. I’ve seen the piles of animals that had been “put to sleep.” It’s heart wrenching.

But spay/neuter and rescue programs have contributed greatly to a decrease in the number of animals in the shelters. In some cases the programs have worked so well the shelters now need to import strays for local people to adopt. USA Today ran a story that an organization in Puerto Rico had shipped over 14,000 strays to the US for adoption.

Spay and neutering campaigns have been so successful in much of the USA — especially the Northeast and Northwest — that shelters need to look elsewhere if they want dogs to offer for adoption.

We shouldn’t be importing pets – and potential diseases – just to keep rescue organizations in business. Canine brucellosis was almost eradicated in the United States, but rescue groups in Wisconsin recently had two dogs imported from South Korea test positive. This is a zoonotic disease which means it can spread to people as well as other dogs.

Several other imported dogs had rabies. At least one dog had been adopted by a family in Pennsylvania before they discovered he was infected. At that point, at least a dozen people may have been exposed.

HEALTH CONSEQUENCES OF SPAY/NEUTER

Spaying and neutering has been good in some ways for society. But what about for the individual animal? There are many health consequences from these surgeries and plenty of misinformation.

“It’s a routine procedure.”
It may be routine for some animal hospitals, but it’s still surgery and, in the case of spaying, major surgery. There are risks from the surgery itself, from anesthesia, and from infection.

“It will reduce behavioral problems such as aggression and wandering.”
It may or it may not. Generally behavioral problems are better corrected through training.

“It can significantly prolong your pet’s life.”
Again, it may or it may not. There are several studies pointing to increased risk of various cancers and orthopedic issues due to spaying and neutering. There is also a study that showed female dogs lived longer if they were not spayed until at least six years of age.

“Spay/neuter can make your dog friendlier and less likely to bite.”
Surgery doesn’t generally affect a dog’s temperament, although there are studies that suggest spaying/neutering can actually lead to more aggression.

“Irresponsible breeding is the root cause of most vicious dog bites and attacks.”
Poor temperament can certainly be inherited, but many dog bites are due to a training issue – either a lack of training that allows a dog to assume an alpha position or training specifically designed to make a dog vicious.

“Spaying and neutering makes happier and healthier pets.”
A study found that “spayed female dogs tend to be more aggressive toward their owners and to strangers than intact females” and there wasn’t much evidence that neutering would stop aggressive behavior in male dogs. I don’t think that sounds happier.

WHAT EXACTLY ARE “SPAYING” AND “NEUTERING”?

Spaying is surgery to remove a female dog’s reproductive organs.

Before the surgery, the veterinarian should draw a blood sample to check the dog’s liver and kidney function because these organs break down and remove anesthesia after the surgery.

If all is well, a female dog is sedated and the belly shaved and cleaned. The veterinarian cuts into the dog’s belly and removes the ovaries, fallopian tubes and uterus. Then the incision is closed with sutures or glue and the dog is monitored as she recovers from anesthesia. Often she will remain at the hospital overnight.

After the dog goes home she will need to be kept quiet and prevented from licking or chewing on the incision.

Neutering is surgery to remove a male dog’s testicles.

As with female dogs, the veterinarian should draw blood to check for liver and kidney function.

Then the dog is sedated and cleaned before the veterinarian cuts into the scrotum. Each testicle is removed and the blood supply tied off, the incision is closed and the dog is monitored as he recovers. The dog should be kept quiet and prevented from licking or chewing on the incision.

Occasionally one or both testicles may be retained inside the body. In these cases the surgery is more involved and can be higher risk. These testicles are at risk of developing cancer so they should be removed or at least monitored via ultrasound.

WHAT ARE THE ADVANTAGES OF SPAYING AND NEUTERING?

• Prevents pregnancy and its risks
• Prevents females from coming in heat every 6-12 months
• Reduces or eliminates the chance of some cancers
• Reduces the risks of non-cancerous prostate disorders and perianal fistulas
• May reduce leg-lifting / marking by males
• May reduce the cost of licensing and/or HOA fees

WHAT ARE THE DISADVANTAGES OF SPAYING AND NEUTERING?

• Costs of the surgery
• Risks of surgery, anesthesia and complications. Studies show about 20% of spay or neuter surgeries have at least one complication. Your dog may die due to the surgery. It doesn’t happen very often, but it’s pretty devastating when it happens to YOUR pet.
• Increased risk of other deadly cancers
• “Increased likelihood of hemangiosarcoma, lymphoma, mast cell tumors, and canine cruciate ligament (CCL) rupture in neutered dogs.”

SHOULD YOU SPAY OR NEUTER YOUR DOG?

I think it should be up to you, based on complete and accurate information and the needs of you and your dog. I also believe you shouldn’t be pressured into a decision either way. Make an informed choice!

A big problem is that alleged health benefits are discussed, but rarely any evidence supporting that viewpoint. Also rarely discussed are the health risks of spaying and neutering.

Risks vs Benefits For Male Dogs

For males, the risks of prostate or testicular problems are fairly low and, if any do occur, the solution generally is to neuter. On the other hand, there are increased health risks due to neutering.

“On the negative side, neutering male dogs

• if done before 1 year of age, significantly INCREASES the risk of osteosarcoma (bone cancer); this is a common cancer in medium/large and larger breeds with a poor prognosis.
• Increases the risk of cardiac hemangiosarcoma by a factor of 1.6
• Triples the risk of hypothyroidism
• Increases the risk of progressive geriatric cognitive impairment
• Triples the risk of obesity, a common health problem in dogs with many associated health problems
• Quadruples the small risk (<0.6%) of prostate cancer
• Doubles the small risk (<1%) of urinary tract cancers
• Increases the risk of orthopedic disorders
• Increases the risk of adverse reactions to vaccinations.”

Overall it seems the negatives associated with neutering are higher than not neutering. The exception being a dog with retained testicles who should be neutered.

If you choose to neuter, you might reduce some of the negatives by waiting until the dog is mature – perhaps a year old for smaller breeds and two years old or more in large breeds.

Risks vs Benefits For Female Dogs

The decision for females is not so easy.

Uterian cancer, mammary tumors and pyometra can all be life-threatening. Pregnancy complications can also be deadly. Spaying can reduce, and in some cases nearly eliminate, these risks.

Also results can be different depending on WHEN they are spayed with early spaying having higher risks of various problems. A longevity study suggests females may live longer if they’re not spayed until they’re at least 4-6 years old. But each heat cycle increases the chance of pyometra and breast cancer.

“On the negative side, spaying female dogs

• If done before 1 year of age, significantly increases the risk of osteosarcoma (bone cancer); this is a common cancer in larger breeds with a poor prognosis
• Increases the risk of splenic hemangiosarcoma by a factor of 2.2 and cardiac hemangiosarcoma by a factor of >5; this is a common cancer and major cause of death in some breeds
• Triples the risk of hypothyroidism
• Increases the risk of obesity by a factor of 1.6-2, a common health problem in dogs with many associated health problems
• Causes urinary “spay incontinence” in 4-20% of female dogs
• Increases the risk of persistent or recurring urinary tract infections by a factor of 3-4
• Increases the risk of recessed vulva, vaginal dermatitis, and vaginitis, especially for female dogs spayed before puberty
• Doubles the small risk (<1%) of urinary tract tumors
• Increases the risk of orthopedic disorders
• Increases the risk of adverse reactions to vaccinations.”

For a little more insight on spaying females, there is a study that concluded shorter lifespan was associated with spaying. They looked at Rottweilers that had an average lifespan of about 9-1/2 years compared with Rotties who lived to at least 13 years old.

Females tend to live longer than males, but it didn’t hold true for females that were spayed before 4 years old.

As they dug deeper, their results showed that how long females kept their ovaries affected how long they lived. If they were at least six years old before being spayed they were 4.6 times more likely to live an exceptionally long life. When they excluded all deaths due to cancer, they found “females that kept their ovaries the longest were 9 times more likely to reach exceptional longevity than females with shortest ovary exposure.”

If you don’t plan to breed your female, spaying would probably be the better choice, particularly if you delay the surgery until your dog is mature.

If you do have a breeding-quality female and plan to breed her, puppies nursing may provide some protection against the risks to unspayed females. Another option for unspayed females is postponing her heat cycles with a steroid, mibolerone.

Each time a female has a heat cycle her body produces increased levels of progesterone which is inflammatory to her uterus. Several heat cycles with this inflammation, particularly if she is not bred, can lead to endometritis, a uterine infection. Mibolerone can delay her heat cycle for up to two years, but must not be used before she’s cycled once naturally.

Once a female’s breeding career is over, spaying would be a good choice. Based on the Rottweiler study, waiting to spay until she is over six years old may help to extend her life.

OTHER OPTIONS

With all the potential health issues caused by spaying and neutering, another option you might consider is hormone-sparing sterilization. These are more like a hysterectomy or vasectomy in people.

A female dog would have her uterus removed, but not her ovaries. She would still have heat cycles due to her hormones, but bleeding is eliminated. Ovarian and breast cancer are still possible, but the risk of ovarian cancer is small. Regularly rubbing her belly – particularly after she reaches middle age – can alert you to any suspicious lumps that could develop into cancer.

For males dogs, your veterinarian would sever the vas deferens – the tube that transports semen. There would still be a chance of testicular cancer or an enlarged prostate, generally later in his life. However these can usually be treated by neutering. In the meantime, he would have benefited by retaining his natural hormones until then.

The problem is that few veterinarians are trained in these procedures. Hopefully that will eventually change.

There are also some non-surgical options. Zeuterin (also labeled EsterilSol in some countries) is an injection that sterilizes male dogs. Unfortunately it’s not currently available from the manufacturer. Suprelorin is an implant for male dogs to prevent fertility. It takes about 2-3 weeks to reduce testosterone and 6 weeks to infertility. It lasts about 6-12 months. Unfortunately it is only available in a few countries, but not in the US or Canada.

Of course, another option is responsible pet ownership. In some countries, neutering is very uncommon or even outlawed. However it does take more effort, especially with an intact female.

CONCLUSION

Spaying / neutering can have profound effects on your dog’s health and longevity. Consider the pros and cons. Don’t let anyone push you into a decision. If you do decide to spay/neuter, wait at least until your dog is fully mature. This may be about one year old for small dogs and two years (or more) for large dogs.

Listed below are some websites with more information:

Gonadectomy – Rethinking Long-Held Beliefs
https://caninesports.com/wp-content/uploads/2021/05/CSP-Gonadectomy-Rethinking.pdf

Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs
http://www.naiaonline.org/pdfs/longtermhealtheffectsofspayneuterindogs.pdf

Aggression toward Familiar People, Strangers, and Conspecifics in Gonadectomized and Intact Dogs.
http://1vv.ba6.myftpupload.com/wp-content/uploads/2021/05/Gonadectomy-and-Aggression-Frontiers.pdf

Assisting Decision-Making on Age of Neutering for Mixed Breed Dogs of Five Weight Categories: Associated Joint Disorders and Cancers
https://www.frontiersin.org/articles/10.3389/fvets.2020.00472/full

Rottweiler study links ovaries with exceptional longevity
https://www.avma.org/News/JAVMANews/Pages/100301g.aspx

Determining the optimal age for gonadectomy of dogs and cats
https://avmajournals.avma.org/view/journals/javma/231/11/javma.231.11.1665.xml

Alternatives to traditional spay and neuter – evolving best practices in dog sterilization
https://ivcjournal.com/spay-neuter-alternatives/

Norway bans pet sterilization without a medical reason
http://www.eurofawc.com/home/19