Spaying and Neutering: New Warnings About Health Problems

Written by Jan on February 3, 2015 – 10:42 pm


Cute little husky puppy isolated on white background Veterinarian Patricia Jordan sent me an excellent article recently that summarizes the new thinking on the negative medical consequences of spaying and neutering dogs, especially when surgery is performed on immature dogs.  This article, written by H.B. Turner, posted with her permission, and previously posted on her blog, is from her ‘Healthful Dog’ magazine

Though restricting indiscriminate breeding is vital to curb overpopulation of pets, we must learn to spay or neuter, whenever possible, when it won’t harm the dog’s health. As with many medical procedures, the risks must be weighed against the many benefits of sterilization. Talk with your veterinarian and decide what to do.


The Spay/Neuter Health Denigration

Sterilization will naturally serve to prevent any unwanted litters. In bitches, spaying will greatly reduce the risk of breast cancer, pyometra, perianal fistula and cancers of the reproductive organs.5

Spay surgery itself carries a somewhat high rate (around 20%) of complications such as infection, haemorrhage and even death.5

Spaying significantly increases the rate of urinary incontinence in bitches….about 20-30% of all spayed bitches will eventually develop this problem. This is believed to be most likely caused by the lack of estrogen that results from being spayed.1

Sterilization of males may reduce some unwanted sexual behaviours, but there are few other proven benefits to neutering a male dog. Testicular cancer is prevented, but the actual risk of that cancer is extremely low (0.1%) among intact dogs. Contrary to popular belief, studies show that the risk of prostate cancer is actually HIGHER in neutered dogs than in their intact counterparts.5

Several studies prove significant health risks associated with sterilization, particularly when done at an early age. The most problematic is a delayed closure of the bony growth plates. This results in an abnormal, skeletal development that increases the incidence of orthopaedic problems like hip dysplasia and patellar luxation. Working and performance dogs, if neutered before maturity, risk the inability to perform the jobs they were bred for.10

But by far the most startling news to surface this year is the result of a study that shows that keeping ovaries to the age of six years or later is associated with a greater than 30% increase of lifespan in female Rottweilers.4  Similar studies in humans reinforce this finding. 7,11

A 30% longer lifespan means that you could have many additional years with your bitch simply by delaying spay surgery until middle-age or later.

Behavioural studies show that sterilization increases fearfulness, noise phobias and aggression. Other well-documented adverse health effects of de-sexing include increased risk of bone cancer, haemangiosarcoma, hypothyroidism, and cognitive dysfunction in older pets. Sterilization confers an increased susceptibility to infectious disease, and also a higher incidence of adverse reactions tovaccines.10

“Potential health problems associated with spaying and neutering have also been identified, including an increased risk of prostatic cancer in males; increased risks of bone cancer and hip dysplasia in large-breed dogs associated with sterilization before maturity; and increased incidences of obesity, diabetes, urinary tract infections, urinary incontinence, and hypothyroidism.” Ref:

In a study of well over a million dogs, information on breed, sex, and age was collected and reported to the Veterinary Medical Database between 1964 and 2003. Results—Castrated male dogs were significantly more likely than other dogs to have hip dysplasia (CHD) than other dogs and spayed females were significantly more likely to have cranial cruciate ligament deficiency (CCLD).

Dogs up to 4 years old were significantly more likely to have HD whereas dogs over 4 years old were significantly more likely to have CCLD. In general, large- and giant-breed dogs were more likely than other dogs to have HD, CCLD, or both.

Prevalence of HD and CCLD increased significantly over the 4 decades for which data were examined. There was no data reflecting the decade-by-decade increase but one might suspect that the significantly increased rate of spay and castration procedures may be a factor in the overall forty-year increase. ref: June 15, 2008 Journal of the American Veterinary Medical Association

“Increased rate of cystitis and decreasing age at gonadectomy was associated with increased rate of urinary incontinence. Among male and female dogs with early-age gonadectomy, hip dysplasia, noise phobias, and sexual behaviours were increased, whereas obesity, separation anxiety, escaping behaviours, inappropriate elimination when frightened…”


Positive for male neutering

1. eliminates the small risk (probably 0.1%) of dying from testicular cancer
2. reduces the risk of non-cancerous prostate disorders
3. reduces the risk of perianal fistulas
4. may possibly reduce the risk of diabetes (data inconclusive)

Negative for male neutering

1. if done before 1 year of age, significantly increases the risk of osteosarcoma (bone cancer); this is a common cancer in medium/large breeds with poor prognosis
2. increases the risk of cardiac hemangiosarcoma by a factor or 1.6
3. triples the risk of hypothyroidism
4. increases the risk of progressive geriatric cognitive impairment
5. triples the risk of obesity, a common health problem in dogs with many associated health problems
6. quadruples the small risk of (<0.6%) of prostate cancer
7. doubles the small risk (<1%) of urinary tract cancer
8. increases the risk of orthopedic disorders
9. increases the risk of adverse reactions to vaccination 13

Positive for spaying females

1. done before 2.5 years of age, greatly reduces the risk of mammary tumors, the most common malignant tumors in female dogs
2. nearly eliminates the risk of pyometra, which otherwise would affect about 23% of intact female dogs; pyometra kills about 1% of intact female dogs
3. removes the very small risk of cervical, ovarian and uterine tumours (5)

Negative for spaying females

1. triples the risk of hypothyroidism
2. increases the risk of obesity by a factor of 1.6-2, a common health problem in dogs with many associated health problems
3. causes urinary “spay incontinence” in 4-20% of female dogs
4. increases the risk of persistent or recurring urinary tract infections by a factor of 3-4
5. increases the risk of recessed vulva, vaginal dermatitis and vaginitis, especially for female dogs spayed before puberty
6. doubles the risk (<1%) of urinary tract tumors
7. increases the risk of orthopedic disorders
8. increases the risk of adverse reactions to vaccination 13

— by Turner, H.B. (2014) The Spay/Neuter Health Denigration. Healthful Dog 1[2]:52-55 This research is further to that in my previous blog To Spay/Neuter or not to Spay/Neuter issued in May

1 Bovsun, Mara; “Puddle Jumping; Canine Urinary Incontinence”; AKC Gazette April 2009–Canine-Urinary-Incontinence/

2 Fry, Mike, “Reflections from the No Kill Conference in Washington DC”:

3 James, Susan Donaldson (ABC News) “300,000 Imported Puppies Prompt Rabies Concerns” October 24, 2007

4 Nolen, R. Scott “Rottweiler Study Links Ovaries With Exceptional Longevity” JAVMA March 2010

5 Sanborn, Laura J., MS “Long-Term Health Risks and Benefits Associated with Spay/Neuter in Dogs”; May 14,2007

6 Thoms, Joy “The Importance of Spay-Neuter Contracts” The Orient Express, Nov, 2009

7 Waters, David J., DVM, PhD, Diplomate ACVS “A Healthier Respect for Ovaries”

8 Winograd, Nathan J. “Debunking Pet Overpopulation” June 29, 2009

9 Winograd, Nathan, “Redemption: The Myth of Pet Overpopulation and the No Kill Revolution in America” Almaden Books, 2nd edition, Feb 25, 2009.

10 Zink, Christine, DVM, PhD, DACVP “Early Spay-Neuter Considerations for the Canine Athlete”; 2005

11 “Retaining ovaries may be a key to prolonged life in women and dogs”; DVM Newsmagazine; Dec 5, 2009.

13 Moore, G.E. Guptill, L.F. Ward, M.P. Glickman, N.W. Faunt, K.K. Lewis, H.B. & Glickman, L.T. (2005) Adverse events diagnosed within three days of vaccine administration in dogs. JAVMA 227[7]:1102-1108

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30 Comments to “Spaying and Neutering: New Warnings About Health Problems”

  1. H B Turner Says:

    Thank you Jan for sharing one of a number articles that we at Healthful Dog Journalzine are proud to share with our readership.

  2. andy greggs Says:

    Most rescue centres especially the RSPCA by policy neuter all animals in there care when will all that stop i wonder

  3. A Wallace Says:

    Neutering needs to be done to stop unwanted puppies.


    about time !

  5. Amanda Says:

    Ya, so now getting your animal fixed is dangerous?? What is going to happen when there are truck loads of animals that nobody wants or that nobody can afford then what

  6. Jessica Oliver Says:

    Thank-you, as a dog trainer this is the science I needed to help explain to people why its OK to delay spay/neutering.

  7. norma jones Says:

    But have to stop all overpopulation of street dogs and strays so surely this has to be done. Also we have 5 dogs 2bitches and 3 boys. Our female pug is spayed after first heat as never wanted to breed from her and new Balkan rescue girl will be done after first heat. 2 boy rescues are now both spayed but were both over 2years but male pug still intact as partner not willing and already had 2 ops for problems. But do worry as so many dogs being stolen esp. This breed for breeding etc. So would like him Done.

  8. Carmen Vega Says:

    Thank you for posting this, yes we do need to reduce the amount of animals that end up on the streets but I love people who open their minds to the fact that sometimes commonly accepted things can actually be dangerous to the pets health as proven by science. Accidental litters (caused by people deciding to wait on spay/neuter) make up a very small portion of the animals in shelters compared to puppy mills and backyard breeders and let’s face it, they’re never going to spay/neuter, the only hope is to not support them directly. I hope people will really think about this and decide whether holding off will be appropriate for them and their pet rather than giving into the pressures of early sterilization.

  9. Gail Hickmott - Greyhound Rescue Says:

    Well this is going to do a lot of good – NOT. I have had over 50 dogs in my life all neutered and spayed and never a problem. Whilst I know there will be times when things go wrong that is the same with every op but please please don’t encourage people to not neuter or spay. I run a rescue and anyone else doing that will not relish the thought of even more dogs to home. There are thousands of dogs a year needing homes, multiple puppies that could be homed if people weren’t breeding.

    The saying why breed and buy whilst others die!

  10. Peppermintwindfarm Says:

    Here’s a novel idea – keep your intact dogs away from the opposite sex during heat cycles- – voilà! No unwanted puppies! I’m concerned that so many people seem unable to cope with being responsible for there own choices & even more concerned with the fascist animal activists that want to dictate that everyone should pay the price for the behaviour of the lowest common denominator.

  11. Jeri Stephens Says:

    Having lost a bitch to hemangiosarcoma due to her being spayed at an early age, I will never do it. Having an intact dog or bitch does require responsible ownership, and that requires education and support. But the cons outweigh the pros to me. My dogs are working dogs, and they remain healthy well into what many would consider “old age”.

  12. Verjean Says:

    I always love the reaction of rescue to these articles…which is “don’t confuse us with the facts…SPAY AND NEUTER!” Overpopulation. Unwanted dogs. Adopt, Don’t Shop. Don’t Buy While Shelter Dogs Die.

    Well, I could add another one…RETAIL RESCUE. But that’s a discussion for another time.

    This is NOT a breeding issue…it is a responsible ownership issue…whether you are “breeding” or just Joe Q Public owning a dog. You are responsible for YOUR DOG!!!

    Decades of research (which continues…) have demonstrated that there ARE REAL risks to spaying and neutering, ESPECIALLY as juveniles. And it doesn’t take a rocket scientist to grasp the concept. So doesn’t rescue desire that these dogs live happy, long and healthy lives??!! I work in rescue as well, and I’ve seen the toll that early spay neuter takes on these dogs…and their adoptive families.

    I have NO problem with any family making the decision to spay or neuter…but I want it to be done with the full and informed knowledge of problems that can be encountered down the road. As the owner of rescued dogs, I have seen them, I have lived them. And I own intact animals as well. And I want the same full and informed knowledge to be given to those owners that choose to keep an animal intact and the responsibility that comes with that decision as well.

    I would say to Gail, that if you have owned over 50 dogs in your life and never had a problem (which I’m doubting…) then you are truly a very lucky individual. I have not owned but perhaps twenty over my almost 60 years…and we have had all sorts of issues, from hip issues and cancers, including hemangiosarcoma. Certainly incontinence issues… Now…that being said, I had a Weim girl spayed at just over a year…who lived to be 15. Had an intact male Dane that lived to 12 and was healthy till the day he torsioned. I have a Pug who was spayed at 12, who will be celebrating her 15th birthday shortly. “Most” of my intact animals have lived healthy lives into their double digit ages…and my sterilized animals have struggled to make 8 or 9 years of age…while dealing with health issues, many of which have been documented through the research above. I have also kept males and females, intact and sterilized throughout the years…and have never had an “oops” litter. Again, it’s not rocket science. When a female is in estrus, you keep her separated from the males…and you keep the males apart as well. Yes, it requires management. If you can’t do that, then you shouldn’t have both genders, or perhaps you are a good candidate for a sterilized dog. But that is the “responsible” part. And the far majority of pet homes, do not keep both sexes…so as long as the animal is responsibly kept in a fenced yard, or in the home…it won’t be producing “unwanted” puppies.

    There are also other choices besides ripping out a female’s uterus, or hacking off a male’s testicles, that would leave the hormones in place, but still eliminate the ability to conceive and produce puppies. Perhaps as these procedures become more demanded by the public, they will be more accessible and cost-effective.

    Again, I’m not saying that people shouldn’t spay or neuter. I just want them to understand that there are risks, and to be aware of and prepared for, those issues should they arise. Rescues for far too long have been placing ALL THE BLAME ON BREEDERS for any health or temperament issues that arise in rescue dogs…when quite frankly, many may have manifested because of the policies RESCUE DEMANDS! Many of the issues that occur in our rescue dogs can be the DIRECT result of our myopic need to spay or neuter AT ALL COST! And there is a cost in far too many cases….

  13. Jan Says:

    Verjean, thank you so much for your comments about spay/neuter. I hope there is a faster learning curve regarding potential health problems than there has been with over-vaccination.

  14. Wende Says:

    Well said Verjean! I had to leave a dog park once because a neutered male dog wouldn’t stop humping my intact male puppy (1.5yr old). Apparently the neutered dog (8 yrs old) would only hump intact dogs according to his owner. I tried to educate her as well as the other owners about the danger of early fixing and the myth of over-population. But no one would listen, i was out-numbered and had to leave the park. It was sad, because my dog loves that park and has many buddies that would not hump him.

  15. DiGascon Says:

    Great post. Thanks Jan. It is not the fact that a pet is un-neutered that causes pet over-population any more than having having a heart is the cause of heart attacks. Instead of penalizing someone for breeding a dog, or having an un-neutered dog, how about we start penalizing the people who are dumping those dogs in the shelters? How about if instead of charging a fee for adopting a dog, shelters start charging a fee for surrendering a dog! Responsible breeders aren’t the only ones alienated by many, so are the people that are getting pups from them. The real problem is the people who aren’t properly educated when getting a dog.

  16. Jan Says:

    DiGascon, I’ve always believed that licensing a dog should include some education, let getting a license to drive.

  17. Holly Says:

    About 10 years ago I read a “literature review ” of neutering vs intact dogs (male / female). Never altered a dog since! But in all honesty while I was living in college poverty in the ’70s I had a bitch that I couldn’t afford to spay and she did end up with pyometra . Scared the hell out of me, she almost died! So now I have intact boys. They get along famously!

  18. Colleen K Edson Says:

    I have a 4 month old chihuahua male. My vet is recommending I neuter him at 6 month otherwise he may be a marker. Are there any health issues with neutering early in a small puppy such as a chihuahua? Thanks for any information you have on this. Colleen Edson

  19. Jan Says:

    Colleen, first, neutering early won’t necessarily prevent marking. Maybe it will; maybe it won’t.

    Vets used to think that neutering around 6 months improved long-term health but now they know that it doesn’t. It can make it worse. Here are some good articles: Wait until his growth plates are mature.

    If the same vet is giving you vaccinating advice, please read this: And especially this: It’s very important.

    Thanks for writing.

  20. Christina Keller Says:

    Is there any insight on vasectomy and ovary sparing operations? How do these fit in with all the other opinions and research out there?

  21. Heather Says:

    I have lived most of my life with unaltered males and females at the same time and have NEVER had an oops!! It takes patience and vigilance during those couple of weeks as she cycles, but it is the least I can do for my sweethearts. I want vasectomies and hysterectomies or tubal ligations to become the norm!! We need to demand that these procedures are routinely taught at ALL veterinary schools!! It’s a no brainer!!!!!!

  22. Pros and Cons of Spaying and Neutering Your Golden — Golden Retriever Rescue of Southern Maryland Says:

    […] Spay and Neuter Pros and Cons […]

  23. Jan Says:

    Heather, I totally agree. A few vets do them, but they are few and far between.

  24. Jan Says:

    Christina, I doubt if there’s any research. So few vets are doing it, although I don’t know why. If you find any research, please let me know. They do compare intact dogs to neutered/spayed and I suspect much of the results are the same. It’s the cutting off of hormones that cause the problems.

  25. Case Says:

    While this is insightful information, what fails to be taken into account is the “everyday life” aspect that almost makes a proactive approach necessary. I have 2 purebred Skye Terriers, one of which I got spayed 3 weeks after she finished her first heat. The other, who is a year younger, hasn’t had her first heat yet so we’re just waiting with doggie diapers at the ready.

    If my oldest girl sees a squirrel and we’re out on a walk she will want to pull and dart; it’s just a Skye’s instinct(s). If the leash breaks and she hauls off and I can’t catch her, there’s no preparing for something like that. We’re training her not to, but she’s not even 2 and Skyes are a very stubborn, yet very intelligent and loving, breed, so it will take time. Dog leashes and harnesses aren’t indestructible and 100% reliable, so I know that, should something like that happen, she won’t come back pregnant with some random male’s babies. “Real-world dog life/living” scenarios need to be applied since most of us dog owners don’t keep our dogs in a bubble 24/7.

    Spay/neuter: pros but, allegedly, more cons. Don’t spay/neuter: known pros and cons. Doesn’t seem like there’s any winning with either choice :/

  26. Darla Haydin Says:

    I do not intend to spay may female Sheltie until she is older!!! Thank you all for the info that’s made me certain of my decision!

  27. RD Says:

    I always loved the “talk to your verterinarian” part, as if talking to the fox guarding the henhouse, i.e the one who stands to make a profit on this surgery is honestly going to get a 100% unbiased answer! That’s like asking a car thief if you should park your car near by and leave the keys in the ignition while you go shopping!
    Dogs in the UK, Sweden and many other countries are not spayed and neutered, their owners learn how to manage their dogs properly.
    I do not have this unnecessary surgery done on my giant breed dogs, they do not mark, the males do not fight, roaming is prevented by locked doors and a LEASH, marking is a housebreaking issue.
    Belly bands train to stop marking if it happens.

    I firmly believe the dogs should retain what they were naturally born with unless a clear, immediate medical NEED requires something be removed.

    Most pet dogs are already spayed and neutered in the USA and yet the dog bite epidemic seems to grow in leaps and bounds, the fact that studies have shown females who are spayed can become more aggressive if they already had a tendency, that is probably because females do produce a very small amount of testosterone that is blocked by estrogen, removing the estrogen allows that small amount of testosterone that is made in accessory glands- to “take over”

    There’s so much we don’t know about the complex hormone systems in biology that we are fools interfering with this on a whim, sex hormones do a lot more than just get used for reproduction.

    As far as pet overpopulation goes, start with prohibiting the tens of thousands of IMPORTED stray stree dogs coming into our country from Turkey, Mexico, Iraq, Afghanistan etc that are flooding rescue and shelters who are selling them.

    There are a number of expose’ articles on bringing these dogs and puppies in from overseas, Golden Retrievers by the hundreds from Turkey- and being sold by California shelters and others.
    While we have even one dog in a shelter in our country NO dogs should ever be IMPORTED from foreign countries into rescue, breed placement groups or shelters!!!

  28. J Wolf Says:

    With pet overpopulation being a problem here in the US, why don’t veterinarians offer vasectomies for male dogs as an option? Just wondering.

  29. Cecilia eastwood Says:

    Responding to Cases comment re neutering her Skye terrier because she takes off on lead I.e.escapes or breaks lead and you are concerned she will mate while away from you. This sounds like a bit of a feeble excuse I am sorry to say. As you point out, none of us live in a bubble with our dogs. The advise in the UK used to be, not to walk unspayed bitches whilst in season in order to eliminate the risk. Of course if you don’t have a garden this may sound less reasonable but at least take them out at times when fewer dogs are about and make sure you have a good, strong and secure lead and harness of which there are a huge number on the market. My dog, a Samoyed, loves squirrels too and dogs and other wildlife and is large and very headstrong and energetic and he has never once escaped off his lead when I have been walking him. I am a lightly built female, so if I can manage then I am sure you can. Unfortunately these days many people want to do exactly as they please, unneutered dogs or no and will insist on taking in season bitches out at popular walking times and to dog parks. Think again please before you do this as it is a big deal for the owners of unneutered male dogs and their owners. A season lasts around three weeks at the most twice a year. Entire male dogs can’t switch there hormones on and off like this. It can cause aggression between male dogs when a bitch in season comes around as well as being a risk for her as far as accidental mating is concerned.. So please be reasonable and if you must take her out, do it at a sensible time and not anywhere where you know there will be dogs about.

  30. Jan Says:

    I’ve asked vets about this and as far as I can tell, they just haven’t bothered to learn how. A few have but they’re hard to find.

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