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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Spay/neuter and the association with cancer in dogs: part three

Updated: May 13th, 2019


Spay Neuter Golden Retriever: Early spay and neuter have several profound long-term effects for one of our favorite breeds.

“Reproduction is a risky affair.”

“Reproduction is a risky affair” is the attention-getting opening line in one of the studies I’ll review today (Hoffman, 2013).

But before we go through the new studies, let’s review my previous articles on this topic. They have been generating some controversy, and with good reason — this is a touchy, political subject!

In my first article, we discussed that sex hormones can promote some cancers (mammary and perianal adenomas), and that early spay/neuter surgeries effectively remove the sex hormones, and therefore can help prevent these cancers. We also talked about why a spay should be considered at time of mammary tumor removal, as dogs that are spayed within 2 years of the mammary tumor development had a survival advantage. Finally, we revealed the results of a recent systematic review of the published work on neutering and mammary tumors, which revealed the actual evidence that neutering reduces the risk of mammary tumors to be weak.

In my second article, I explored the idea that sex hormones may be PROTECTIVE again certain cancers, including very aggressive cancers such as osteosarcoma, bladder transitional cell carcinoma, prostate cancer, lymphoma, and heart tumors.

Of course, there are many factors that can influence cancer development in the body, as Dr. Dressler and I make very clear in our book The Dog Cancer Survival Guide. The reason I’m going into such detail in this series about the effects sex hormones do (and don’t) have on cancer development is because it’s important to understand each factor fully. There are some things we, as dog lovers, cannot control, and there are others that we can. It’s important to be fully informed as we fight the number one killer of dogs: cancer.

So let’s look at the latest study, one I’ve mentioned but haven’t yet fully discussed: the 2013 publication by Torres de la Riva et al called Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers.

The Effects of Neutering Goldens on Cancer and Hip Dysplasia

The Torres de la Riva study looked at veterinary hospital records and reviewed those of 759 Golden Retrievers to see what health conditions are associated with spay/neuter surgeries.

Patients were classified as intact, neutered early (< 12 months old) or neutered late (>12 months old). Let’s look at the results:

  • Hip dysplasia (HD)
    • Of early-neutered males, 10% were diagnosed with HD
    • This was two times (2X) the occurrence than intact males
  • Cranial cruciate ligament tear (CCL)
    • NO cases of CCL in intact males or intact females
    • 5% early-neutered males
    • 8% early-neutered females
  • Lymphoma (LSA)
    • Almost 10 % of early- neutered males diagnosed with LSA
      • This is three times (3X) more than intact males
    • No LSA cases in late-neutered males
    • No effect in females
  • Mast cell tumor (MCT)
    • No cases of MCT in intact females
    • 6% late-neutered females
    • No effect in males
  • Hemangiosarcoma (HSA)
    • 8 % late-neutered females
    • Four times (4X) times more than intact females and early-neutered females
    • No effect in males

According to this study, spay and neutering is associated with disease development in Golden Retrievers. Here’s a quote:

“For all five diseases analyzed in the present study, the disease rates in males and/or females were significantly increased when neutering was performed early and/or late. When a disease occurred in intact dogs, the occurrence was typically one-fourth to one-half that of early- and/or late-neutered dogs. When no intact dogs were diagnosed with a disease, such as with CCL in both sexes and MCT in females, the occurrence in early- and/or late-neutered dogs ranged between 4 and 8 percent of the sample.”

Read more about all the things that put our dogs at risk in the book. 🙁

While it is tempting to apply the results of this study to other breeds, this study was based on one breed from a single hospital database (UC Davis). We do not know if the effects of spay/neutering will be true for other breeds or all dogs. Perhaps different cancers and different joint diseases will be affected in other breeds or dogs. But since Goldens are one of the most popular American breeds and a common service dog, this is still important info even if it applies only to Goldens. (I see a lot of Golden in my Oncology Service at work.)

Still, to me, as a veterinary oncologist, this study highlights that we have much to learn about how spay/neuter affects cancer in dogs. The decision to spay or neuter and the timing of that surgery is much more complicated than we’ve thought it was.

This is especially enlightening when we realize that these surgeries are far less common in European countries than they are here. As Dr. Dressler and I remind ourselves and our clients in our book, there is more than one way to practice medicine.

I think it’s time to start having more discussions about spaying and neutering than we currently do. Especially when I look at the details provided by a second study that came out this year, titled Reproductive Capability Is Associated with Lifespan and Cause of Death in Companion Dogs (Hoffman, 2013). This study out if the University of Georgia and looked at a whopping 40,139 case from the Veterinary Medical Database (VMDB), and it reveals even more complications!

Spay/Neuter Affects How Long Dogs Live

In the Hoffman study, it was revealed that sterilization (spay/neuter) significantly affected survival of the 40,139 cases under review.

The average age of death was 7.9 years if intact, and 9.4 years if neutered.

So here it looks like sterilized dogs had an increased life expectancy (males 13.8%, females 26.3%).

Sterilized dogs were LESS likely to die of infectious disease and trauma, vascular disease, and degenerative disease.

BUT sterilized dogs were MORE likely to die of cancer and immune-mediated disease.

Why are sterilized dogs LESS likely to die of infectious disease? One thought is that the female sex hormones progesterone and estrogen can be immunosuppressive (they can suppress the immune system). Does avoiding infection lead to longer lifespans?

Sterilization increased the risk of death due to cancer, but did not increase risk for all specific kinds of cancer.

In this study, spayed females were unlikely to develop mammary cancer.  But there was an increased risk to develop transitional cell carcinoma, osteosarcoma, lymphoma, and mast cell tumors. There was no effect for squamous cell carcinoma, melanoma, and prostate cancer.

Unlike the Davis study, this study did not look at age of spay/neuter. In addition, all these cases were ones referred to teaching hospitals, which may not be representative of the general dog population. This is highlighted by the shorter overall lifespan in these dogs than seen private practice.

Does socioeconomic status come into play? Owners that cannot afford spay/neuter may also lack resources to provide medical care for disease later in life. So are dogs owned by people who can afford to spay/netuer associated with better medical care, so they appear to live longer?

We now have new evidence that demonstrates that dogs who are spayed/neutered are at increased risk of dying of some cancers. And we see that at least in Goldens, the cancer rates in males and/or females were significantly increased when neutering was performed early and/or late.  We must continue to examine when dogs are dying and WHY.

Unlike in Europe, most dogs in the United States are spayed/neutered before one year of age, and often without much discussion on the part of the veterinarian and the dog owner. It is time to start having more discussions about the very real pros and cons of spay and neuter, and the timing of these surgeries.

Live longer, live well,

Dr Sue

Other Articles in This Series

Spay/neuter and the association with cancer in dogs: part one

Spay/neuter and the association with cancer in dogs: part two

Leave a Comment

  1. Pam Johnson on February 1, 2018 at 7:22 pm

    I find your articles very interesting because I had a Tibetan Spaniel, neutered at 5 years of age, that had a rare Cutaneous Lymphoma at the age of 14. Now, I’m wondering if it’s because we had him neutered.
    Also, my female Tibbie was spayed at 2 years of age after having some puppies but lived a pretty healthy life till 15 when she developed cataracts and dementia. Both were fed the same diet and raised in the same environment. She never developed mammary tumors or have any kind of cancer. Just age related diseases.
    I find it fascinating and will keep reading your posts to see if there are any new findings on when it’s best to spay/neuter a dog.
    I now have two Tibetan Terrier puppies that I plan to keep intact. My girl around 2 years old and my boy maybe never. That’s presently my best educated guess for giving them a long healthy life. Thanks again for sharing your knowledge on this issue with everyone!

  2. Deb on September 16, 2014 at 2:42 pm

    Hello Dr. Ettinger,
    I’m very glad I read your blog as I have an 8 month old standard male and I have been torn over whether to neuter. What do you think would be an acceptable age? Also I believe this dog also developed a vaccine induced tumor- rhabdomyosarcoma. Long story short the vet lied about where she injected the vaccine so nothing was ever reported. I went to this clinic for 15 years and felt very betrayed- I find it difficult to trust my new vet because of what happened. Any input you can give would be greatly appreciated.

  3. Lynn on October 17, 2013 at 6:17 am

    Hi Dr. Ettinger,
    I was doing research about spaying my female golden and came across your website. I was hoping to get your opinion as to spaying. My girl is now 17 months old. She had her first heat cycle when she was 14 months old (unless she had a silent heat). I was planning to spay her before her second cycle. But, the study that UC Davis published in February has terrified me. Now I feel like I fall into the “late spay” group with an even more increased risk for hemangiosarcoma. After losing three out of three goldens to cancer, two early neutered died of hemangiosarcoma just before 10), I would do anything to prevent this in my Lucy. In light of that study, and any other research you might be aware of, what do you recommend doing at this point? My options are to have her fully spayed immediately to reduce the risk of mammary cancer, not spay at all, or remove her uterus only and leave her ovaries. I am aware of the increased risk of mammary cancer if the ovaries are left, which also adds to my confusion.

    I would appreciate ANY input you might be able to provide. I realize that you do not have a crystal ball, but I am just trying to diligently question people with significant experience with Goldens and canine cancer to add to my own knowledge. I feel like this will the best way for me to be able to make the most informed decision for my girl. What would you do if she were your dog?

    Please let me know your opinion as soon as possible… THANK YOU!

  4. Jean on September 20, 2013 at 4:42 pm

    I didn’t spay my beauceron at the recommendation of my vet and she developed mammary tumors (adenocarcinomas) when she was eight years old. Three years four surgeies, two rounds of chemo, well over ten thousand dollars ad many tears (neither surgery or a top diet or supplements come cheap) we’re still fighting this. She was ALWAYS fed a top notch raw diet and supplements, no exposure to cleaning chemicas or lawn chemicals, and spring-fed water that is routinely tested. So I guess you need to pick your poision – don’t spay and deal with cancer or spay and deal with a different type of cancer….

    Me? Next time I’ll spay and place my bet on a top quality diet, low exposure to environmental carcinogens, exercise and clean water!

  5. Sabrina on July 8, 2013 at 2:59 am

    Hi Dr. Ettinger,
    This blog was very informative and I had a question I am praying you might be willing to answer. My 4yo Boston Terrier was diagnosed with Lymphoma (stage 5) in July 2012. She was treated with chemo and a Bone Marrow Transplant, doing well 6 months post-transplant. She went into heat once since transplant and seems to still be ok. However, the oncologist wants to spay her before her next heat as she fears she will come out of remission during heat as some chemo-treated dogs seem to. My question is, this breed is usually prone to MCT, and due to the carcinogens and radiation, mine is probably a higher risk for all cancers. I understand the breast cancer advantages of spaying but am concerned that the spay would put her at greater risk for many less treatable cancers. Can you offer any thoughts?

    • Dr. Susan Ettinger on August 2, 2013 at 3:30 am

      His Sabrina,
      Glad to hear that your dog is doing well post transplant (was it done at NC State?) I understand your concerns for spaying, and there are pros and cons. The preventative benefits of mammary cancer are typically when the spay is before the 2nd heat. It is not clear how long a pet needs to stay intact to have the protective effects for oth cancers. In one study they looked at spay after 1 year, so she likely has had some protective benefit from being 4. If your oncologist is concerned about the effect on her current lymphoma, that probably takes priority over the potential for other cancers, but no one knows. And also remember,intact pets get cancer too so keeping them intact in no guarantee. So no easy answer or recommendation.
      Thanks for reading, and I wish your dog a very very long remission!
      All my best, Dr Sue

  6. Lori on July 2, 2013 at 3:32 am

    So many issues to consider. I lost a Newfie to Osteosarcoma at the age of 9 and he was neutered at 6 months. It is absolutely heartbreaking to watch this horrible disease take its toll on your dear family friend. It is what bought me to you. My dog now- A pure bred St Bernard, I had originally planned to neuter between 6 and 8 months, got postponed because he suffered bloat at 4 months(a whole other huge topic I had to learn a lot about in a short time and realizing that I probably had the youngest dog to ever suffer bloat because there is absolutely nothing available as far as care plans and recovery and feeding plans for young dogs with tendency to bloat, the emergency vet said she had never done bloat surgery on a dog that still had his puppy teeth) , the surgery and recovery slowed his growth and our vet suggested we wait a until he had finished growing stating that early neutering can affect head size and bone growth in St.s. Then when he turned a year and a half we had a blood work up on him prior to scheduling his neutering and he showed elevated creatine (sorry if I spelled wrong) and abnormal kidney levels and elevated protein levels and there was consern about his adrenals sorry I may have the details wrong here I don’t have it in front of me but the vet said that possibly a raw diet could contribute to the protein levels and kidney levels. he is not on a raw diet but after nearly losing him to bloat he is on a grain free diet – (Orijens and tiki dog at the time) which tends to have higher protein than other dog foods, she said to change his food and re test , he now eats Blue Buffalo grain free large breed. So we will see about that…meanwhile my daughters black lab went into heat and I learned what its like to have a very aroused st bernard around the house ( please everyone save the comments about having two intact dogs in my house, I am fully aware of how irresponsible my daughter is, and I am for that matter, for allowing her dog to remain intact, another reason why we should never believe our kids even when they are 18 that they will take care and be financially responsible for the dog they MUST have.) We kept them separated and I do not believe any litter will result (it has not been 63 days yet fingers and toes crossed) Excuse my meanderings here, but getting down to it, I am wondering if I should neuter my male St. at all, given the high occurrence of osteosarcoma and other cancers in large breeds as well as dementia and other brain ailments. With the possibility of the looming kidney disease that his blood work pointed toward I have lots to think about.-Side note he (my dog) does not seem sick or have any visible health problems, he east well, drinks well, eliminates well etc. Knowing now what I did not then he is on a much higher quality diet and gets supplements of salmon oil daily. I was quite ignorant raising my Newfie and did not realize the correlation of crappy food to health -nor did I for myself for that matter at that time.
    Thank you for putting issues however passionate each side may be out there and for shedding light on unpopular choices and for translating all of the scientific research findings in to real language for the non scientists out her. I always look forward to your blog posts.

  7. Petchiro on June 20, 2013 at 5:05 pm

    While i realize that in some areas an over abundance of animals is a real issue, BUT i am continuosly hearing of many shelters in many areas of the country being so short of adoptable pets that THEY ARE IMPORTING FROM OTHER COUNTRIES!!!!! So while i agree that most people should NOT own an intact animal of any kind (and quite frankly most of them should be spayed and neutered themselves to prevent unwanted humans from being brought into this world), spaying and neutering should not be shoved down the throats of every pet owner in the Country. And being a responsible owner myself (I train and show ALL of my dogs) I am getting sick and tired of the animal “rights” groups and individuals constantly trying to force spay/neuter on everyone including trying to create mandatory spay/neuter laws in many States (including mine!). I won’t force you to keep you pet intact, don’t try to force me into spaying or neutering mine. I am so glad that all of this new research is finally coming to light and the brave and forward thinking vets like Dr. Sue are willing to step forward with it (many of us in the dog world have been aware of some of the research for quite some time now). If you wouldn’t remove the ovaries and testicles in a young child due to the adverse affects it would have on their development and health, why in the world would you think it would be ANY different for an animal? Common sense people…even without the research!

    • Dr. Susan Ettinger on June 26, 2013 at 3:49 pm

      Thanks Petchiro! I appreciate the support!
      All my best, Dr Sue

  8. Pam Wilkinson on June 15, 2013 at 9:29 pm

    Yeah Sarah! I will continue to spay and neuter too no matter what, until the pet over population is 90 percent better in America. It is so devastating to know 14,000 dogs and cats are killed every single day and each dog/cat is as wonderful as mine, I know. I am a responsible person and would never allow pups or kittens to be born yet I do know accidents happen so I spay/neuter right away. I also have older pets get cancer and this is how I found this wonderful resource that has helped incredibly so to keep them comfortable with diet and vitamins for years past any onocologist could imagine. I personally have cancer and the lessons I have learned from my wonderful animals has also prolonged my life just by diet alone. It’s amazing. By the way, I’m not sterilized.
    Thank you too Dr. Sue for your comment. Yet I really feel lawn fertilizer and diet is more of a culprit for pets to get cancer. Or maybe it’s just age. I do love your diet suggestions that have prolonged comfort and life.

    • Dr. Susan Ettinger on June 18, 2013 at 3:31 pm

      Thanks Pam. Wishing you and your pets continued good health!
      Dr Sue

  9. Donna on June 15, 2013 at 1:59 am

    sorry – one more thing – I have my dog on keegan water – High ph

  10. Donna on June 15, 2013 at 1:37 am

    I have a golden that has had 3 DIFFERENT cancers in the past 2 years – he has had 3 surgeries 4 months of chemo – I presently have him on the “cancer diet” – it is a praying game I suppose – he was neutered at 10 months of age – I did not have him microchipped (did not want any foreign body in him given risk of golden cancer) I went to great lengths to research breeders – his mom is from usa and dad from europe ( hoped that would eliminate over breeding – his dad had only arrived 1 month earlier and mine was from first litter) this has been a real heartbreak for us bc he seems to be a tumor factory – just recently heard that chemical neuter can be done and it maintains a small amount of testosterone in dog – not sure if that changes anything for future dogs – havent had chance to really look in to it…..

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