For decades, the standard approach to spay and neuter in dogs has been to have it done asap – ideally before a female’s first heat cycle or before a male has the opportunity to breed. The given reason for this approach was that it would decrease the pet’s chance of cancer – specifically mammary cancer in the females and testicular/prostatic cancer in the males, but it’s probably more likely that its main motivation was as a means to manage pet overpopulation (a totally different blog post). 

The problem with that reasoning was that it failed to take into account whether or not the dog was at a particularly high risk of developing those cancers in the first place, and, moreover, if there were negative impacts of removing the sex organs at such a young age. 

I’m incredibly excited about some newly published research from the University of California – Davis College of Veterinary Medicine. This study analyzed the increased risks of various cancers and joint diseases in dogs who were sterilized early vs. those who were not. Their study includes 35 breeds, as these were the breeds which had a large enough sample size to be statistically significant. They DID also evaluate these relationships in mixed-breed dogs, but they will be publishing this research in a separate report. 

What Did They Find?

For the majority of breeds evaluated, time of sterilization had no impact on risk of joint disorders or cancers.

HOWEVER, for some specific breeds/sexes, there WAS enough evidence to indicate a statistically significant increase in disease – Australian Cattle Dog (female), Beagle (male), Bernese Mt. Dog (male), Border Collie, Boston Terrier (male), Boxer, Cocker Spaniel, Collie (female), Corgi (male), Doberman Pinscher, English Springer Spaniel (female), German Shepherd, Golden Retriever, Irish Wolfhound (male), Labrador Retriever, Miniature Poodle (male), Standard Poodle (male), Rottweiler, Saint Bernard (female), Shetland Sheepdog (female), and Shih Tzu (female). 

They were kind enough to summarize the entirety of their recommendations, based on their findings, in a convenient table!  Check out the full article and scroll to Table 1.

What Do I Do With This Information? 

As a veterinarian, I’ve always based the time of spay/neuter on a conversation with my client. If my client is not willing to manage an intact pet, we schedule the sterilization between 4-6 months. If my client IS willing to manage an intact pet, I’ve been recommending that they wait until physical and sexual maturity, which of course is later for large-breed dogs than small-breed dogs. Now that I have this handy table, I will share this with my clients as well. 

If you are a responsible breeder of one of the at-risk breeds, I would recommend providing this research paper and explanation to your puppy buyers. If you typically write a letter to their future veterinarian, I would include a statement such as, “Based on recent research from the University of California – Davis College of Veterinary Medicine, it is suggested that waiting to spay/neuter [BREED] until [TIMEFRAME] is likely to decrease their risk for joint disorders and/or cancer.”

What About Breeds Not in the Study?

There are, of course, hundreds of breeds that were not able to be included in this study. At this point, we don’t know which of these breeds are at increased risk and which aren’t. Additionally, many dogs are mixed breed or crossbred, and the relationship is likely even more complicated in those individuals because of the variability in their genetics. 

My main takeaway points are the following: 

1) It is not accurate to uniformly say that spaying/neutering before 6 months of age is in the best interest of the patient or that it’s even safe. 

2) The time to spay/neuter is a decision that should be made on an individual basis with each family and their veterinarian. If your family does not agree with your veterinarian on this point, I would recommend that you find another one.  


Yours in healthy, responsibly-bred puppies,

Categories: BreedingDogs

Dr. Kristina Baltutis

Dr. Kristina is a reproductive medicine enthusiast with an okapi obsession. She lives in Burlington, NC with her dogs, cats, chinchilla, and spouse.


Ruth Sperling · March 15, 2021 at 12:03 pm

Hi Dr. Baltutis,
Thanks so much for this article. May I ask your thoughts on vasectomy procedures for a male standard poodle? Would this be a procedure you’d recommend to maintain hormones for male? Thank you again, Ruth

    Dr. Kristina Baltutis · March 16, 2021 at 3:53 pm

    Hi Ruth!

    Based on the UC Davis study, their data says that keeping a male standard poodle intact for at least 23 months decreases his risk for joint disease and cancer as compared to neutering earlier. Therefore, if this particular male needs to be sterilized earlier than 23 months, I would definitely recommend vasectomy. If it isn’t a problem to keep him intact until 23 months, his risk of joint disease and cancer does not increase if he is neutered at that point.

Linda Jo Law · April 15, 2021 at 3:42 pm

I have a standard poodle female she’s about 30 lb right now I was going to spay and spay her next month but someone told me to wait till she’s at least a year for her growth plates to be completely mature but she does have an umbilical hernia that doesn’t seem to be causing any problem I mean she runs and jumps and everything fine and I don’t feel like I did before what is your advice in this situation

    Dr. Kristina Baltutis · April 15, 2021 at 3:53 pm

    Hi Linda!

    Based on the UC Davis study, in female standard poodles, there was no increase in prevalence of cancer or orthopedic disease associated with time of spaying. In that case, other factors take priority, such as are you prepared to manage an intact female through 1-3 heat cycles? Is the hernia large enough to cause her risk of complications? Best of luck!

      Theresa · July 21, 2021 at 4:09 pm

      We have a 14 month old male English Shepherd. He learns quickly and responds well ….most of the time. We have thought to leave him intact but what advantages come to him and us if we were to have him neutered and at what age would we want that done.

        Dr. Kristina Baltutis · July 21, 2021 at 5:12 pm

        Hi Theresa!

        Looking at related breeds, I would predict that neutering him anytime after 12 months would not change his predisposition to orthopedic disease or cancer (to our current knowledge).

        The relationship between neutering and behavior is complicated and somewhat unpredictable. He may be less likely to “roam” and therefore may be less prone to injuries or diseases associated with roaming. However, neutering may have no impact on his behavior at all. Neutering eliminates his risk for testicular cancer, although most testicular cancers are benign. Neutering decreases his metabolism, which typically equates to him being more likely to become overweight, but of course this is manageable by monitoring his diet.

        The main advantage to you is that you wouldn’t need to manage an intact male – i.e. monitoring him to ensure that he does not cause any unwanted pregnancies. This is the most significant reason to neuter a male dog. Neutering will not necessarily make him listen any better or make him easier to train.

        I hope this helps!

Fiona Caie · August 25, 2021 at 6:05 pm

I have a 12 week old Sproodle (SpringerXMinature Poodle) I would appreciate your expect advice as to what would be the best age to have her neutered. Hate to say this don,t have much faith in my own vets going by my other dog who has passed away. Not easy for me to change vets either as I do not drive and the vet I am with is within walking distance. Getting taxis too and fro from vets more so as the dog ages would be very expensive for me.

    Dr. Kristina Baltutis · August 26, 2021 at 12:07 pm

    Hello Fiona!

    If you are comfortable managing an intact female while she is in heat, my recommendation would be to have her spayed after 1 year of age. If you are not comfortable managing her while she is in heat, there is no data that specifically indicates that spaying her between 6-12 months would be detrimental.

Matt Connolly · September 9, 2021 at 12:24 pm

Hi Dr. Baltutis!
I have read many conflicting reports regarding a safe time to spay my 6 mo. English Shepherd. My veterinarian has recommended staying within the 6-7 month window but ive talked with several owners of the breed that say its best to wait up to 1 year to allow their joints and bone structure to fully develope. Not to mention the risk of spay incontinence comes into play. I think she is already undersize for the breed and slow in her development but want to do whats easiest on her. Should her current smaller “runt” status alone deter me to wait even longer?

    Dr. Kristina Baltutis · September 12, 2021 at 2:55 pm

    Hi Matt!

    You’ve probably found conflicting reports because there isn’t a clear answer – it’s definitely an area of continued research.

    A dog’s “runt” status alone does not change my opinion of when it’s best to have them spayed.

    The first question I ask my clients is the following: Are you willing and able to manage an intact female dog through one or more heat cycles? This involves two main components: 1) managing the dog dripping bloody discharge for 1-2 weeks with each cycle; 2) maintaining constant vigilance to ensure that she does not get accidentally pregnant. Some people are ok with these management considerations while others are absolutely opposed to it.

    If the answer to the above question is “No” then for most breeds I recommend having the female spayed around 5-6 months. There is not significant enough research to indicate that spaying at that age would be detrimental.

    If the answer to the above question is “Yes” then I typically recommend waiting until physical and sexual maturity (1-2 years depending on breed).

    Hope this helps!

Marilee · September 13, 2021 at 11:42 am

Thanks for this information and responding to each and every person with a question. This study that was conducted is really great to have. I have an 8-month old male Whoodle. According to the breeder contract, we must have him neutered by 1 year of age unless I can talk them out of it and explain why we want to wait. His mom was a whoodle and dad was a standard poodle so we think he’s about 75% poodle if our math is correct. According to the study, if we go with the standard poodle as the predictor, it’s best to wait until just under 2 years of age? . Would you push it to as close to 1 year of age for neutering him if no choice? Thank you so much!

    Dr. Kristina Baltutis · September 13, 2021 at 2:30 pm

    Hello Marilee!

    The currently available data is inconclusive related to your pet’s situation. That being said, my personal preference is that medium and large breed dogs are neutered after they are physically and sexually mature. Best of luck!

Nila · September 17, 2021 at 7:42 am

Hi Dr Baltutis,
I have a 5 month old male spoodle – 50% miniature poodle and 50% spoodle – and the vet showed me this report. I read other aspects of this report pertaining to cross breeds like mine and apparently with smaller cross breeds the risks are lower than with the pure breds which means I can still neuter at a younger age. However, my puppy exhibits fear and anxiety when going on walks and in unfamiliar situations and the vet raised the concern that we are best to delay desexing to allow his male hormones to come through as it helps with his fears. I read that after neutering a dog before male hormones have come through, fear aggression can be a real problem and a risk factor for those timid dogs. It would be good to know your thoughts on this.
Thanks so much!

    Dr. Kristina Baltutis · September 17, 2021 at 12:29 pm

    Hi Nila!

    I have a couple thoughts that relate to your situation, I hope they help!

    First, fear and anxiety in dogs and puppies have many, MANY contributing factors. Although the influence of hormones is definitely one of them, it is not the most important factor.

    By far, the most significant factor when helping a puppy (or dog) work through fear, anxiety, and/or stress is socialization – which is controlled introduction to a wide variety of new experiences. The most critical time for this in a puppy’s life is from 3 weeks to 12 weeks, but continues to some extent throughout their life.

    Bottom line, regardless of whether a puppy is neutered early or late, the way they are introduced to new experiences has a much more dramatic impact on their fear, anxiety, and stress.

    For more information about puppy and dog socialization, check out

    Second, the main reason to neuter a male dog at all is for pet population control. There are minimal positive health benefits for the dog himself. True, it does prevent benign prostatic hyperplasia and testicular cancer, but these can *usually* be resolved with neutering at the time of diagnosis. Most canine testicular cancers are benign, although it is possible for them to be malignant.

    Therefore, I would not hesitate to delay the time of neutering in a puppy showing signs of fear, anxiety, or stress, with the caveat that I would not expect delay of neutering alone to be enough to help the pup through his fears.

      Glen Campbell · May 22, 2022 at 3:59 pm

      Hi Dr. Baltutis

      We have a male and female border collie pups. They are siblings and just turned 4 months old.

      We do not want them to breed and I’ve noted Hank is occasionally mounting Sadie briefly when they are playing. I gently but quickly discourage this behavior. I’m pretty engaged with both of them through out the day; they have an active lifestyle.

      I don’t want to injure Hank’s health by neutering him too early, but he seems like he might be sexually active sooner than later. Given these facts can you recommend neutering and spaying time line, please?


        Dr. Kristina Baltutis · May 24, 2022 at 2:15 pm

        Hi Glen!

        Thanks for reaching out. Both male and female border collies may benefit from having the time of spay/neuter postponed to 11+ months. However, we definitely don’t want these siblings to breed, so in this situation I would recommend spaying Sadie around 6 months of age and delaying Hank’s neuter until 11+ months, or whenever he starts to exhibit unwanted behaviors such as urine marking.


        Dr. Kristina Baltutis

Joyce · November 4, 2021 at 1:53 am

Thanks for this information. I have a female aussiedoodle (half standard Australian shepherd, half standard poodle). At 17 weeks she weighs 31 pounds (I don’t know if that’s beneficial info or not🤷🏻‍♀️). Based on what you’ve written, am I correct in understanding I should wait until she is sexually and physically mature before spaying? (I can manage her being in heat.) At what age is that likely to be? (How do I know when she is matured?) Thank you!

    Dr. Kristina Baltutis · November 9, 2021 at 10:24 am

    Hi Joyce! For a medium-sized aussiedoodle, my best estimate would be to wait until at least 12 months and at least 3 months after her first heat cycle. The first heat cycle can occur any time between 5-12 months.

Laura · April 20, 2022 at 5:38 pm

I appreciate your response. I have 6 month-old, 6.5 lb., female Maltipoo scheduled to be spayed in 6 days. Such mixed information regarding when is best! I have no problem taking her through a heat cycle. I’ve also read it is best to wait until physical maturity. What would you advise?

    Dr. Kristina Baltutis · April 21, 2022 at 8:42 am

    Hello Laura!

    For both Maltese and Toy Poodles, there isn’t any conclusive evidence indicating that the time of spay impacts joint disease or risk of cancer one way or the other. We can only make assumptions that a cross of the two would have similar risks.

    J · January 16, 2024 at 4:53 am

    Hi I have a Maltese Shi Tzu. She is just over 13months old. (Born Dec12/2022) She had her 1st heat cycle at 7months and had what I beleive was a Pseudo pregnancy after that. I did not want to have her speyed until her growth plates were closed so have waited until 12 months. Only to read this research saying that ShiTzus have increased other cancer risk if speyed after 12months so they should be speyed after 24 months. The reason for this is not clear. Does the cancer risk drop back to normal or less at 24months? What percentage? Then what about the maltese part or her? I read mammory cancer risks increases in maltese and or mixed breeds after 2nd heat to 26%? What are we to do ? Is the risk of other cancers greater in her because of the ShiTzu in her such that you would wait until she was two years old before speying? Or is does the fact she is a small mixed breed mean the risk is minimal? Should we spey before the second heat or wait til after she is two?. Is the risk of mammory cancer the greater risk here? How common are the other cancers by comparison? It is so difficult to know what is best for her. Any advice appreciated.

      Dr. Kristina Belton · January 21, 2024 at 5:02 pm

      Thanks for your comment!

      I know it can be overwhelming and confusing. You just want to do what’s best but it’s so hard to know what that is!

      The short, unsatisfying answer is that we have very little data on how time of spaying affects mixed breed dogs. In other words, we just don’t know at this point.

      That being said, in general, for small breed dogs the risk of mammary cancer is usually higher than the risk of joint disease, so I typically recommend having those dogs spayed earlier rather than later.

Pamela Boyd · June 7, 2022 at 12:18 am

What are your recommendations on spaying an Aussiedoodle? She is she is 7 months old right now. I am okay with taking care of any of the needs she may have, I just want to make sure to have her spayed at the time that is best for her, not me. Thanks In advance for your advice.

    Dr. Kristina Baltutis · June 8, 2022 at 4:26 pm

    Hi Pamela!

    For both Aussies and Poodles, there is no clear evidence that the time of spay or neuter will impact the incidence of orthopedic disease or cancer, so we can infer that the same would be true for Aussiedoodles. My recommendation would be to wait until she is physically mature, typically between 9-12 months. One approach to take is to wait for her to complete her first heat cycle, and then wait an additional 3 months before having her spayed. I hope this helps!

      Pamela · June 8, 2022 at 5:09 pm

      Thank you so much! I’ll will follow your advice and I appreciate your opinion so much!

Sarah · June 10, 2022 at 9:03 am

Hi! I have a 14 month male goldendoodle (he is about 80 pounds) and have been holding off on neutering for his health to about 15 months. I have seen this study and don’t know if we need to try to wait longer because of his poodle mix? (I would say he’s 75% poodle). It’s so hard to know what is best! Any advice would be appreciated

    Dr. Kristina Baltutis · June 19, 2022 at 5:21 pm

    Hi Sarah!

    There’s probably not one “right” answer. If you are comfortable continuing to wait, that is probably the more conservative option!

Kokilla Maniam · October 2, 2022 at 7:34 am

Hi doctor. I need your expert opinion on spaying by GSD puppy. I went through few articles which revealed that the best time to spay her would be at age of 1 yr. old to prevent Musculoskeletal problems and it prevents mammary malignancy and pyometra (some of the important ones) Some parents are discouraging me. What is your expert opinion doctor

    Dr. Kristina B · October 3, 2022 at 3:25 pm

    German Shepherds were one of the breeds for which there was a statistical difference in the UC Davis Study. The recommendation of that study is to delay the time of spaying in female German Shepherds until beyond 23 months of age.

Gene Bedford · November 27, 2022 at 11:54 am

I should receive my female Giant Schnauzer towards the end of February. Currently I have a 4 yr old neutered male Shepherd. I waited until he was 2 yrs of age before I had him neutered after speaking to the breeder I received him from. She said it would be beneficial for his growth plates & studies show possibly preventing some cancers later in life. My question is should I wait this long for my Giant Schnauzer? Since he’s neutered & she won’t be around other dogs unwanted litters shouldn’t be an issue. I’m reading this is beneficial for other breeds but am unable to locate anything on this breed.

    Dr. Kristina B · December 4, 2022 at 5:23 am

    Hi Gene,

    You’re correct that there are many breeds for which there isn’t specific information. In general, I recommend delaying the time of spay/neuter in large breed dogs until 18-24 months if the family is prepared to manage an intact dog. Looking at breeds that are somewhat closely related to giant schnauzers, such as dobermans and german shepherds, it would be reasonable to conclude that giant schnauzers may benefit from delaying time of spay/neuter.

Leesha Baker · April 1, 2023 at 12:46 pm

I have an Old English Sheepadoodle (1/8 Standard Poodle) who is about 9 months and currently in her first cycle. Is there a benefit in waiting for her to finish a second cycle before spaying? I am debating 3 months after her first cycle or waiting for three months after her second cycle. I am not looking to breed or have surprise puppies, but obviously I want her hips to be healthy. She is currently 67 pounds.

    Dr. Kristina B · April 2, 2023 at 4:38 pm

    Hi Leesha,

    Thank you for your comment. There isn’t specific data on your situation at this point. That being said, I typically recommend delaying the time of spay/neuter in large breed dogs until 18-24 months if the family is prepared to manage an intact dog. In your girl’s case, there’s no specific evidence to indicate that it would increase her risk of hip disease by spaying her after this current heat cycle. However, to err on the side of caution, it would be more conservative to wait one additional heat cycle.

Kim Wilson · March 26, 2024 at 12:13 pm

Dr. Kristina Baltutis, I am a breeder and an LVT. I recommend waiting for physical maturity to all my puppy families, as do all Windsprite breeders I know. My question is a bit more complex and hope you will answer it for me. As an LVT, all the vets I’ve worked for have suggested having females, who have had a heat cycle to wait approximately 3 months into anestrus so the uterus can return to a smaller size for less complications. I’m at a point now where I have bitches who need spaying, but they are on different schedules. First heats in my lines are approximately 18 months of age. This sets them up fairly nicely to be spayed if not a breeding prospect to have their growth places closed when after their first heat. I also have older bitches, I’m retiring from breeding or didn’t grow out as expected and want to keep them healthy by spaying. Each bitch is a bit different in their cycles one is 7 months between, another is 8 months. When is it the best time, hormonally to spay a bitch after a heat. I was just reading about some number of days that it takes for all hormones to return to a baseline before they start preparing for the next cycle. Do you have any data on that, refer a study, or knowledge of the most appropriate time after a heat cycle to spay that won’t cause any issues with the reproductive hormones being at a certain level. Thank you very much for your consideration, and this article which I will share in our breeding community and education as I mentor other breeders.

Warmest Wags,

Kimberly Joy Wilson LVT, CDBC, CEBC, CPDT-KA, FFCP, LSHC-S

    Dr. Kristina Belton · March 28, 2024 at 5:47 pm

    Hey Kim!

    Thanks for your question. In dogs, progesterone returns to baseline approximately 2-2.5 months (55-75 days) after ovulation, which is probably why you’ve heard to spay them 3 months after a heat cycle. I personally like to postpone it 4 months after a heat cycle, unless they historically have a short cycle, for an added buffer. Let me know if you have any follow up questions!

Susan Bell · June 21, 2024 at 11:49 pm

I acquired a Boston Terrier puppy on 6-12 at age 7 1/2 months. She had not previously gone into heat and my plan was to spay her in mid to late August.. At the time we picked her up the breeder told me her growth plates were nearly closed and would need another 1-2 months at most. Well, she went into heat on 6-17. Can I still schedule her spay for August or would you advise waiting a bit longer?

    Dr. Kristina Belton · June 22, 2024 at 11:51 am

    Hi there Susan!
    I typically recommend waiting at least 3 months after the end of a dog’s heat cycle to have her spayed, so based on that I would recommend scheduling in October or later.

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